"Brian Watson" wrote in message

A contributor to The Robert Elms Show on BBC Radio London has just
claimed there are secret underground train lines between Buckingham
Palace and various other London sites.

Nifty conspiracy theory, or fact?

There are plenty of semi-secret tunnels connecting government buildings
in central London, and some may indeed have connections to the
Underground, but I doubt that there are trains running in them. At most,
they may have airport-style electric buggies for people and 'cargo' (eg,
boxes of files).