Michael, during the sixties I lived up in Scotland, and they have always had trick-or-treat at Hallowe'en, but they call it 'guising'. One blackens the face, no particular costume, and it's expected that the caller performs a little song or turn for some sweets etc. I think this was also done for centuries in Ireland, and the Irish emigrants during the Famine took it to USA. I think also it has its origins in the old Celtic 'samain' which is/was celebrated at this time. I do love all these traditions! I must say I'd hate to live near London, you're obviously a 'town mouse' and I'm a 'country mouse'!