My hands also get cold in ski gloves - I wore mittens when I went snowboarding (with a liner), in reasonably warm conditions and my hands were only just warm enough.
When I spent some time in actual Siberia I had heat packs in my (three layers of) gloves and bought a lot of coffees to hold but it's not really that practical for cycling in london.
I can't remember if you've already tried this last year, but what about the method of warming up the gloves before putting them on? (leaving them above a radiator to grab in the morning).
It's not a long term solution if you go touring again, but should make your commute a little more bearable.
My hands also get cold in ski gloves - I wore mittens when I went snowboarding (with a liner), in reasonably warm conditions and my hands were only just warm enough.
When I spent some time in actual Siberia I had heat packs in my (three layers of) gloves and bought a lot of coffees to hold but it's not really that practical for cycling in london.