I see this one every day as our office recently moved to Bethnal Green. There are quite a number of clocks on the Tube with roundels instead of numbers. As far as I know the one at Bethnal Green is the only one where the roundels are gold. Dated from around the 1940′s it was restored in 2009 and you can find it on the Eastbound and Westbound platforms.
Check out TimeOut's post for my four other favourites.
Let me know your favourite Tube station clocks as there are number of lovely ones to choose from.