HD: although I never worked in the tower at Heathrow, you did hear tales of these fire service runs, like the one where there was a slight 'shadow', the controller took the fire truck through it not knowing it was cordoned off with a line of oil drums which ended up scattered all over the place.
Oh by the way, take a look at
Farnborough-aviation-group . They're running a thread on Blackbushe piccies from the past, many from the Bennet era but mostly before.