I can't give a precise date, but sometime in the period 1981-1988 when I was living in Blackheath, S.E. London, on a Saturday morning around 9 a.m. the air raid siren situated, I believe, somewhere in the Woolwich area sounded for about 30 seconds. I went outside (don't quite no why, but still!) to find absolutely no panic whatever and really no acknowledgment that it had happened. About an hour later in Lewisham town centre I was at a bus stop waiting for a bus back to Blackheath when a most strange vehicle in army colours came trundling past, going in the Woolwich direction. It was very long, in sections but not, apparently, articulated, and its width varied in the different sections, which all appeared to be armoured. It went past, and that was it: I think there was a paragraph in the local rag the following week to say it had been a false alarm (phew). In the 1990s I had moved to Cornwall and became acquainted with a local man who had lived in London for many years, during which time he had become a GLC councillor for Islington, and had had had responsibility for civil defence matters. He still did freelance work and, to my astonishment, on the BBC Ten o Clock News one night he presented an item on London and civil defence in the pre-Millennium age. The next time I saw him I told him of my experience but he could throw no further light on it, and had no idea of what the vehicle I'd seen could have been : by this time the GLC was long gone, of course, murdered by Mrs Thatcher.