Second World War Heavy Anti-Aircraft (HAA) Battery, 345m east of Decoy Farm, Mautby


Heritage Category:
Scheduled Monument
List Entry Number:
Date first listed:
Date of most recent amendment:
Location Description:

Statutory Address:
Off Mautby Lane, Decoy Farm, Mautby, Norfolk, NR29 3EJ


Ordnance survey map of Second World War Heavy Anti-Aircraft (HAA) Battery, 345m east of Decoy Farm, Mautby
© Crown Copyright and database right 2019. All rights reserved. Ordnance Survey Licence number 100024900.
© British Crown and SeaZone Solutions Limited 2019. All rights reserved. Licence number 102006.006.
Use of this data is subject to Terms and Conditions.

The above map is for quick reference purposes only and may not be to scale. For a copy of the full scale map, please see the attached PDF - 1455654 .pdf

The PDF will be generated from our live systems and may take a few minutes to download depending on how busy our servers are. We apologise for this delay.

This copy shows the entry on 21-Oct-2019 at 01:38:43.


Statutory Address:
Off Mautby Lane, Decoy Farm, Mautby, Norfolk, NR29 3EJ

The building or site itself may lie within the boundary of more than one authority.

Location Description:

Great Yarmouth (District Authority)
National Grid Reference:


The standing, buried and earthwork remains of a Second World War heavy anti-aircraft gun battery known as YH4 in military records. It is located to the east of Decoy Farm, Mautby Lane, within a wooded area on high ground to the north of the lower-lying marshland of the River Bure, and comprises four gun emplacements, a command post and a sample of its access road.

Reasons for Designation

The standing, buried and earthworks remains of the Second World War heavy anti-aircraft (HAA) battery at Mautby, comprising four gun emplacements, a command post and a sample of the site's access road, are scheduled for the following principal reasons:

* Survival: as a well-preserved Heavy Anti-Aircraft battery which retains its core structures including a command post and four gun emplacements, both retaining evidence of their original fittings;

* Rarity: not only has it been identified as one of a small number of complete or near complete Second World War gun batteries, but it is probably the most complete HAA battery in England constructed with four gun emplacements to the Directorate of Fortifications and Works (DWF) specification drawing DFW55483/1;

* Period: as one of the few obvious and tangible facets of Britain’s wartime air defence system, one which stands testament to a specific form of C20 warfare and to national defence policy;

* Potential: the gun emplacements and command post will enhance our detailed understanding of the construction, function and use of this military site type in Britain, along with Aircraft Command's advances in gunnery and military tactics during the course of the conflict;

* Diversity: although the domestic site and sewage treatment plant have been lost, it is still a legible ensemble, in which the functioning of the gun emplacements and command post is strongly sensed and the military experience readily captured;

* Historic interest: it provides an exceptional insight into the development of anti-aircraft measures during the Second World War, with it being a significant, visible reminder of the nature of home defence during the conflict.


One of the major threats to Britain during the Second World War was the strategic bombing campaigns of the German Luftwaffe. To combat this danger major installations and ports were provided with heavy anti-aircraft (HAA) gun sites and almost 1000 were constructed nationally. The standard weapons deployed at these sites were 3.7 inch and 4.5 inch calibre heavy anti-aircraft guns, operated by almost 275,000 men, supplemented by women soldiers from the Auxiliary Territorial Service (ATS) from 1941 onwards. Along with gun emplacements, which were usually arranged in groups of two, four or eight, the operational structures of a typical HAA gun site consisted of a standard set of components, including a command post, a radar platform, a gun store and a magazine for storing reserve ammunition. A variety of typical military hutting made up the domestic section of the site, usually a combination of Nissen and timber huts placed on concrete building platforms. Most domestic sites also had workshops and garages, and very often a sewage treatment plant. HAA sites were also provided with structures for their close defence, with light anti-aircraft (LAA) gun pits, searchlight emplacements and pillboxes being common. Due to their inflexibility, the majority of Second World War HAA sites were abandoned during the course of the war, but a small number were retained as part of the Nucleus Force and adapted for Cold War use.

As was the case elsewhere in the country (with the exception of London) Norfolk's HAA batteries were organised into Gun Defended Areas (GDAs), each protecting one or more targets or Vulnerable Areas (VAs). The battery at Mautby (known from military records as site YH4) was one of five HAA batteries deployed to defend Great Yarmouth as part of the Yarmouth and Lowestoft GDA. Its extent was identified from an aerial photograph taken in 1945 as part of the Norfolk Coast National Mapping Programme (NMP), which was undertaken between 2002 and 2006. The photograph shows the battery occupying a rectangular-shaped area, aligned east-west, immediately to the east of Decoy Farm, on the edge of the higher ground to the north of the River Bure marshland. Four, square-shaped gun emplacements, placed in a semi-circle on the east side of a command post, are depicted at the east end of the site, while twenty-four domestic buildings with pitched roofs and concrete bases are recorded at the west end. A concrete service road is also documented, running from the site's main gate on Mautby Lane to a loop around the command post, with offshoots to each gun pit. An area of disturbed soil on the east side of the site was identified as the possible remains of a LAA gun pit for the ground defence of the site.

Although the date of the battery's construction is unknown, the square plan-form of the gun emplacements suggests that the operational element of the site was built after the Directorate of Fortifications and Works issued specification drawing DFW 55483/1 in September 1943 for a new form of emplacement that could accommodate 3.7 inch guns equipped with the No 11 Machine Fuze Setter (MFS). Trials undertaken in the summer and autumn of 1943 found that the existing octagonal-shaped emplacement (DFW 55414) gave insufficient space for ammunition storage in relation to the enhanced rate of fire obtained from the new equipment, while the design and siting of the ammunition recesses slowed the crew’s ability to load the gun at the new pace made possible by the MFS. Following discussions at the War Office on 26 August 1943 to settle the final specification, it was concluded that a square-shaped emplacement was required as this form would allow more space for the larger number of spent cartridges created by the faster rate of fire, which could be accumulated in the corners of the gun pit during operation. The new design, of which variants were also probably built, was to have four ammunition recesses and, instead of an on-site magazine, a trench shelter was provided for each emplacement, together with a personnel shelter, to which the gun pit would have easy access.

While it is known from military records that the batteries deployed to defend Great Yarmouth were in existence by June 1942, it is not clear whether a battery at Mautby had been built by this date. An analysis of Great Yarmouth's Second World War defences, which was undertaken as part of the Norfolk Coast NMP, suggests that site YH4 was originally located at the town's racecourse, probably as a mobile HAA unit, before being moved 4km to the west, to Decoy Farm, Mautby, at a date post-September 1943.

An aerial photograph taken of the site in July 1946 shows that all the structures depicted on the 1945 photograph were still standing, with the presence of motor vehicles illustrating that the site was still in use. Under the Nucleus Force scheme three of Great Yarmouth’s batteries were retained to form part of the post-war HAA layout. The batteries at West Caister (YH1) and Gorleston (YH2) were Battle Headquarters (BHQs), with their weapons remaining in situ, while Mautby (YH4) was designated an ‘Off site’, with its weapons and fire-control instruments stored in nearby depots. However, with the development of nuclear weapons and surface-to-air missiles rendering conventional anti-aircraft artillery of this type obsolete, the site was abandoned shortly afterwards.

An aerial photograph taken in March 1955 shows that most of the domestic buildings and structures associated with the sewage treatment works had been demolished, while aerial photographs taken in September 1970 and June 1981 show that tree planting had taken place to the south of the access road, around the two southern emplacements and to the west of the command post. Tree planting has subsequently taken place around the two northern emplacements and in the area of the former domestic site.

Since the late C20 the command post has been used by a local gun club, with an internal wall being removed to create an indoor shooting range.


Principal elements: the standing, buried and earthwork remains of a Second World War heavy anti-aircraft gun battery known as YH4 in military records. It is located to the east of Decoy Farm, Mautby Lane, within a wooded area on high ground to the north of the lower-lying marshland of the River Bure, and comprises four gun emplacements, a command post and a sample of its access road.

Description: the remains of the HAA battery stand within an irregular shaped area with maximum dimensions of 207m east-west by 116m north-south. The four gun emplacements (centred at NGR TG 48807 10989, TG 48825 10968, TG 48820 10940 and TG 48803 10917) stand at the eastern end of the site, arranged in a semi-circle on the east side of the command post. Facing east towards Great Yarmouth, the emplacements, which measure 13m square, are all identical, with concrete block walls and a single gateway placed in the corner closest to the inner service road. The walls stand 1.7m high from the internal floor of the emplacement and are cement rendered externally. All are externally protected by earthen banks, which survive to a height of about 1.2m. The emplacements all retain gun holdfasts embedded within concrete centre sections of the emplacement floor. The presence of 10 vertical members protruding slightly above the floor of the gun pit suggests that the holdfasts are a version of Holdfast AA Mounting No 2 which was capable of accommodating both 3.7 inch and 4.5 inch guns. The remainder of the floor surface, although largely concealed by vegetation, is believed to be tarmac. Internal ammunition recesses with concrete block walls and reinforced concrete roofs project from the centre of each emplacement wall, with each emplacement having four recesses in total. Placed outside each emplacement, immediately to the right-hand side of the entrance, is a semi-sunken crew shelter with concrete block walls and a reinforced concrete roof. Their entrances are positioned away from the emplacement and lie perpendicular to the emplacement entrance itself. The interiors, which are revetted with corrugated iron and brick, are accessed by a short flight of reinforced concrete steps set between concrete block blast walls. The command post (centred at NGR TG 48790 10955) stands at the centre of a 39.6m radius semi-circle formed by the gun emplacements. Constructed from brick with a reinforced concrete slab roof, it is a roughly rectangular, single-storey, semi-sunken structure with a north-south alignment. Although its design largely follows that of DFW 55402 (the main type of command post used for permanent 3.7 inch and 4.5 inch guns from 1941) the Mautby example differs slightly in that it has a different entrance arrangement and a flat-roofed annexe, probably a later addition, on its west side. The concrete bases of various instrument mountings survive in three linked areas on the east side of the building, which is enclosed but open to the sky. In operation these mountings would have housed an identification telescope, the predictor (a mechanical computer) and height finder. These open areas also provide access to the interior of the command post through three doorways. Two are now (2018) bricked-up, with the southernmost doorway adjacent to the height finder mounting now (2018) being the single point of access. Concrete steps descend into two square-shaped rooms at the south end of the building. These in turn provide access to the main interior space which comprises a long, rectangular room, the central part of which originally housed the plotting room. The internal walls that separated the plotting room from the transmission room to the south and the telephony room to the north were removed in the late C20 to create an indoor rifle range.

A concrete service road runs from the former site entrance on Mautby Lane (NGR TG 48471 10964), at the western end of the site, to the gun emplacements at the eastern end. From the former entrance (now enclosed by a late-C20 barred gate) it curves in a south-east alignment for a distance of about 207m before turning north-east to form a tear-drop shaped loop around the command post, with offshoots to each gun pit.

Extent of Scheduling: the area of protection, which is shown on the accompanying map extract, includes four gun emplacements, a command post and a sample of the battery's access road. It does not include the area formerly occupied by the domestic camp or sewage treatment plant, as the survival of these features is fragmentary.

The scheduled area is bounded to the east and part of the south side by field boundaries formed by tree lines and hedge rows. The remaining section of the south side opens onto woodland while the north side opens onto agricultural land. A 2m buffer has been included along the north and south sides of the access road for the support and protection of the monument.


Norfolk Heritage Explorer, NHER Number 29751: World War Two Heavy Anti Aircraft Battery at Decoy Farm, Mautby, accessed 17 September 2018 from
Albone, J, 'An Archaeological Assessment of the Second World War Heavy Anti-Aircraft Battery at Decoy Farm, Mautby, Norfolk', (2016), Norfolk County Council
Albone, J, 'An Archaeological Assessment of the Second World War Heavy Anti-Aircraft Battery at Decoy Farm, Mautby, Norfolk', (2018), Norfolk County Council
Albone, J, Massey, S, Tremlett, S, 'The Archaeology of Norfolk’s Coastal Zone: Results of the National Mapping Programme', (October 2007), pp137, 140


This monument is scheduled under the Ancient Monuments and Archaeological Areas Act 1979 as amended as it appears to the Secretary of State to be of national importance. This entry is a copy, the original is held by the Department for Digital, Culture, Media and Sport.

End of official listing

Your Contributions

Do you know more about this entry?

The following information has been contributed by users volunteering for our Enriching The List project. For small corrections to the List Entry please see our Minor Amendments procedure.

The information and images below are the opinion of the contributor, are not part of the official entry and do not represent the official position of Historic England. We have not checked that the contributions below are factually accurate. Please see our terms and conditions. If you wish to report an issue with a contribution or have a question please email [email protected].