I don't know if you are aware of this exhibition Richard but it looks right up your street (pun intended). Just round the corner in Chancery Lane too.
Free exhibition showcases 500 years of rare and beautiful maps
If you like looking at old maps, then you'll love a new exhibition that's recently opened in the City of London, showing a range of maps dating from the 15th century onwards.
www.ianvisits.co.uk