Paul Robson wrote to uk.transport.london on Sun, 14 Nov 2004:

Why not have a simpler system ; like an insurance disk on
the windscreen ?

I believe in some countries they do something very like that - visible
proof of paid-up insurance on the windscreen or number-plate. Not a
micro-chip that can go wrong (or its reader could go wrong), but some
dog-tag or other.
--
"Mrs Redboots"
http://www.amsmyth.demon.co.uk/
Website updated 6 November 2004 with new photos