I reckon Sealskins are the best on the market,... but there's still room for improvement. They do keep your hands dry for a few hours, but not all day,... and using them every day you'd wear them out very quick.
Luckily in this climate you prob only need them for 20 odd working days the entire year,...
I'd still get 2 pairs, 1 for mornings and a fresh pair for after lunch. Throw both pairs on the radiator to dry when you get home at night.