The Heathrow 23cm radar was mounted on a concrete tower adjacent to Terminal 1 car park in the central landside area by the exit/entrance to the tunnel giving access to the terminals from the A4 and M4 spur. It was known as the "Car Park" radar and was removed from service and its replacement operates from Bovingdon, near Hemel Hempstead. To give better low level coverage in the absence of the 23cm radar another Raytheon ASR10 was installed southside near to T4, this supplemented the Raytheon ASR10 east of what was T2, The Queens Building and T1, these both replaced the Watchman which was sited where T5 is now. For interest the Watchman replaced the Plessey AR1 sited just north of T3 and the Cossor ACR6 which was sited south of T3 where AOSU is or was in 2010 when I retired. The building of T5 also nessesited the resiting of the DF and the Rx site.