Having been closed for 6 or 7 years, The Mansion House - http://www.oakalondon.com/ - re-opened in March as a modern bar-style pub on one side and a "Pan Asian" restaurant called Oaka on the other.
It's the only London pub to feature the full range of beers from Peterborough-based Oakham Ales. When I called in, there were 10 different ales on the hand pumps, ranging in strength from 3.8% to 7.5%, as well as a wheat beer, a craft lager and a real cider.
Beer is served in 1/3rd and 2/3rd of a pint glasses, as well as the normal measures, and the bar is open until 1.30 am on Saturday nights.
The pub is about 100 yards from Kennington underground station. Cross the road as soon as you come out of the station, turn right and you'll see it straight ahead of you.
As it's only just opened it's a bit difficult to know how busy it's going to be, but if it gets too crowded we can always go to The Old Red Lion, a traditional pub right next door