I've blackburn front lowrider and rear racks, as well as some Shimano DX cantis. Not in London though so would need to post. Also have Campag 10spd bar end shifters, ITM touring bars/DiaCompe brake levers and Velo Orange ahead stem I could sell as a whole.
36h wheelset preferably on shimano hubs
Front or rear racks
v brakes/cantilevers
Also needed (just incase you have both);
27mm seatpost (preferably black)
25.4 dropdowns