Nevermind. It was pretty effortless to write a quick patch for this. Just replace the Handmark Monopoly file 'monopoly.rb' with the version in the zip file (link below) to get the British property names and currency. Remember to backup your old one if you want to go back.
It's not 100% perfect. Some names have been padded out with spaces and others have been abbreviated. Also the 'pay $50' button on the 'get out of jail' box still reads '$' and not '£'.
There's probably a couple of other minor things but overall it seems fine.
Link (137kb):
http://www.upload2.com/?cmd=_viewer&...4d55b95cf6.zip