This is somewhat off-topic as it's not a totally classic-computer event,
but there should be at least one old-ish (1970's) piece of computing
machinery there.
There is an HPCC (Handheld and Portable Computer Club) Conference in
London (Imperial College) on 13th/14th October this year. Details are on
the HPCC website (
http://www.hpcc.org), there's an obvious link from the
homepage.
Attendance is free, and you don't have to be a member of HPCC. But you do
have to register befroehand, we need to know how many are coming, and
indeed who. Detials of how to do that are on the website too, don't
e-mail me, OK :-)
-tony