One of the biggest problems when you're working on sash windows is painting the damn things and not having them stick, in the process pulling out all the draught-proofing.
I used to use Dulux 30-minute paint, but it was only available in white. Have since discovered B&Q's own range of 'quick drying' paint, which is available in a range of colours. Says it's touch-dry in 4 hours, but I've painted the one I've made for the study and it was touch-dry in an hour and a half!
Goes on a bit thick, though, and the gloss finish comes out more like a satin finish, but I've never liked a high gloss finish anyway and it's totally out of character on an old building.
Good price as well.
It's meant I've managed to get two coats on the window in a day. Sorted.