there goes a tenner lyrical question

["Brian J. Dillard" <dillardb@pilot.msu.edu>]

i love this track for its wry humor, amusing details and bouncy 
melody. but i've never understood the closing lines.

*there goes a tenner, there goes a fiver, remember them, that's when 
we used to vote for him (dun-duh-duh)*

however, the other day it suddenly occurred to me that britain changed 
to decimal currency sometime (in the 70s?) and, if i am not completely 
mistaken, although old-style coins are still in circulation, old-style 
notes are no longer valid currency. could these lines be an ironic 
postscript to the story, in which kate and her conspirators find out 
that the money they've stolen is no longer valid? or am i completely 
off-base? and, if so, anybody else have a theory about what those 
lines mean?

brian dillard
dillardb@pilot.msu.edu