Operations Block (Building 27) RAF Northolt Hillingdon & Buildings 007 and Buildings 112 RAF Northolt Hillingdon Greater London

The Operations Block at RAF Northolt is of a standard design (1161/24), the same as many
constructed at airfields in the mid 1920s. It is a bungalow with a plain utilitarian character
and architecturally it is of limited conventional interest. However, it is of significance for its
history, use and particularly its association with the Battle of Britain. Prior to the outbreak
of the Second World War the airfields of Fighter Command had been divided into a series of
Groups throughout the country and each group was divided into sectors. Northolt was the
principal airfield in Sector Z and formed part of the significant 11 Group whose airfields
took the main Luftwaffe attacks during the Battle of Britain and which was most heavily
involved in the fighting. The sector operations room at Northolt would therefore have been a
key part of the chain of command during the Battle by allowing the commanders to plot,
monitor and strategically plan the battle. The Operations Block was in contact via telephone
and teleprinter with radar stations, other Operations Blocks, Observer Corps stations,
Fighter Command Filter Rooms, balloon depots and many other authorities so that positions
of incoming enemy fighters could be tracked and squadrons based at Northolt scrambled.
This complex network of information formed part of the famous Dowding System of Defence
and the Northolt Operations Block is particularly of interest as it acted as the prototype
Sector Ops Block to be copied elsewhere. In addition its close proximity to Fighter
Command HQ (Bentley Priory) and 11 Group HQ (Uxbridge) also added to its importance at
a time when the telephone network was nowhere near as extensive or reliable as it is today.
However, although Building 27 is clearly of historic interest and it was recommended for
listing at Grade II by English Heritage (following their thematic survey of military aviation
sites) this recommendation was withdrawn and it now has no statutory protection (listing or
Conservation Area status).
Various secondary alterations such as the replacement of almost all the windows, the recovering
of the roof, the removal of the Ops Room gallery (‘dias’) and the levelling of the
blast banks slightly reduce the integrity and significance of the building as does the fact that
Northolt’s Operations Room was relocated away from Building 27 during the Battle of
Britain. This was due to the vulnerability of the building from a direct hit during a Luftwaffe
bombing raid on the airfield but it is also of course a recognition of the crucial importance
held by the Operations Blocks and the Dowding System (the worlds first integrated Air
Defence System) during the Battle of Britain. This is also demonstrated by the number of
films such as ‘Angels One Five’ which have included numerous scenes of women from the
WAAF pushing markers on large maps in Operations Rooms. It is now difficult to gain a
clear sense of how the Northolt Operations Block would originally have appeared and films
such as this, as well as the restored building at RAF Duxford, provide a vivid reminder.
It is not the purpose of the current document to clinically establish the significance of the
Northolt Operations Block or whether it is worthy of listing. The key purpose is to record,
interpret and investigate the structure (although of course to some extent appreciating the
significance of the building is a key part of understanding and interpreting it). The recording
has been undertaken at Level III prior to its removal in the redevelopment of parts of the
airfield (Project MoDEL). The work has provided a record of the building and it has also
allowed further investigation into its historic form and comparison with other similar
Operations Blocks (eg at RAF Duxford).

Oxford Archaeology (OA) have been commissioned to undertake a programme of building
recording at RAF Northolt. The recording is to take place prior to demolition and/or
redevelopment of the site as part of Project MoDEL (Ministry of Defence Estate London).
Project MoDEL is the rationalisation of MoD Estates across London which will see the disposal of
surplus sites and the centralisation of various centres within the RAF Northolt base. This work
means that much of RAF Northolt is to be redeveloped with much demolition of existing buildings
and the creation of new purpose built facilities.
This report is concerned with Building 007, originally the central heating station for the airfield,
and Building 112, originally constructed for use as a decontamination facility. Both buildings are
of a standard design and are similar to many constructed at airfields throughout Britain in the
inter-war period. These buildings are unlisted, but due to their historic interest, and that of RAF
Northolt generally, they have been recorded at Level II prior to their removal in the
redevelopment of parts of the airfield.
Although architecturally these buildings are of limited conventional interest, they are significant
for being part of this airfield. RAF Northolt played a significant role during World War II. Both
Building 007 and 112 had very specific functions and their form can be seen to follow this
accordingly. Through their study, our understanding of how early military airfields functioned is
enhanced.
The overall aim of the project is to create for posterity an archive record of the buildings
concentrating on their construction, history, development and use. The work aims to record,
interpret, understand and explain the buildings. The other main objective is to deposit this record
(both the report summarising the building and the primary archive itself) in publicly accessible
repositories.