London Borough of Barnet

The London Borough of Barnet was a part of London somewhat proximate to Heathrow Airport. A lay-by on the Barnet Bypass was the site of one of the last remaining police boxes in England. Tegan's aunt's car once broke down there, within a few yards of what appeared to be the aforementioned police box but was in fact the Doctor's TARDIS — which itself had materialised around the Master's TARDIS. The Watcher first appeared to the Fourth Doctor in this borough, as well. (TV: Logopolis)

Behind the scenes

 * This location was established by a sign immediately to the left of the TARDIS which reminded citizens "PLEASE TAKE YOUR LITTER HOME". Unfortunately, in the finished programme, the sign is right next to a litter bin — thus begging the question as to what the bin is supposed to be used for...
 * In real life, though not established in Doctor Who fiction, the airport is some 34 miles north-northwest of central High Barnet, the major conurbation of the borough. High Barnet is also some 15 miles north of Ealing, the setting of The Sarah Jane Adventures, and Ealing is separated from Barnet by only one borough, Brent.