A number of people have mentioned silk inners in the ‘warmest gloves’ thread so I thought I would try a pair. Absolutely brilliant - they make a real difference and do not feel bulky.
I also have a pair of synthetic inners but do not use them as they feel bulky and awkward. I got my silks from Hein Gericke £13. Best to go to the shop and try them on. I take a med/large in gloves but needed XXL in the silks.
Another advantage is that they are thin enought to do most things with them on, so you can wear them to unlock the bike, open the top box , put on your helmet etc. so they keep you warm at times when you could not normally wear gloves.
Big running shop around the corner from Holborn tube, Runners Need it is called, but it is on the corner of High Holborn and Proctor. According to their website there is also one at King’s Cross, but I do not know how big that store is.