Simon, I've got an old Shimano 600 (the predecessor to Ultegra) front mech sitting in one of the toy boxes.
It was designed for use with downtube shifters, so doesn't have the right cable pull ratio to work with STI units. If it's any good to you, you can have it for a cup of tea on a club run.
I have a band type 105 which is as new, it is for steel tubed bike (ie skinny tubes) you are welcome to have it if you think it will fit for sti use. I live in South croydon or can bring it along to the club run.
Sounds like it should work - is there any chance you could stick it in some wrap and an envelope in the post to me? (Natwest, 3rd floor, 2 Waterhouse square, EC1N 2TH) Will give you some cash by return to cover it and postage ... Sorry not doing club run for a while as just acquired a daughter!