As far as I'm aware Chris, Gaggs are still in business repairing speedometers (but only magnetic?) If you need a chronometric repairing, then Russell at Chronometric Services (also in Nottingham) should be able to assist. HTH
I'm expecting this Jaeger speedo back from Phil Woods this week. I've used them a few times with satisfaction. Standard price for a refurb is £70 including post back. I didn't want it cosmetically finished as I'll respray it and add my own dull plate bezel. http://www.chronometricspeedos.co.uk/page3.html