Barry Salter wrote in uk.transport.london on Sun, 01 Jan 2006 13:03:35
+0000 :

I think the TSSA might disagree too...But then they're the only one of
the three not to have had a *National* walkout since the late 40s or
so...

1926 General Strike, actually (though there have been RCA/TSSA ballots
in favour of industrial action since then).

Dave