So it is mucky, muddy weather and despite avoiding mudguards previously,I ordered a pair of Gilles Berthoud fenders, they were delivered within a few days and arrived well packed in French newspaper, (I nearly threw out the small bag of fittings), and with a catalogue but no instructions. However fitting was straightforward and took about an hour or so.
The rear mudguard is predrilled for the chainstay bridge and the fitting struts, my Bob Jackson World Tour already has drilled chainstay and seatstay bridges (vertically for mudguard rather than horizontally for brake fitting) which meant that I just needed to drill a 5mm hole in the position for the seatstay bridge - the stainless steel is quite slippery to drill, so I suggest drilling a small pilot hole from inside to out before then drilling the 5mm hole from outside in. I bought 40mm mudguards which needed just a slight squeeze to fit in between the chainstays while still providing adequate clearance for 700x32c tyres. I used 7 or 8 washers to space out the mudguard from the chainstay bridge (circled in red). Because the bike has horizontal rear dropouts, the tyre now has to be deflated before fitting or removing - not a big issue given that I would only ever be taking it off in the event of a flat anyway. This could probably be avoided if I didn’t space the fitting to the chainstay bridge, but wouldn’t have looked so neat.
I ordered the “short” version of the front mudguard as I have no intention of fitting a handlebar bag. Again fitting was fairly straightforward because of compatibility with the World Tour build. The front mudguard mounts to the forks using a fitting held from a bolt screwed through the brake mount in the fork crown, it sounds complex but results in a really neat fit - this is only suitable for a 1” column though.
I wasn’t too worried about the stripe up my back, the main reason for fitting the mudguards was to try to keep the drivetrain a bit cleaner and the difference is really noticeable and riding in the wet is definitely more pleasant.
----- Edited 18th January 2013 -----
See the post on fitting a Brooks Leather mudflap here. Definately a worthwhile upgrade!