Abacus is a fairly new venture, right in the middle of the City on Cornhill. Going through the doors, it looks very much like your standard trendy bar à la Pitcher & Piano. But in the basement is a dancefloor and the place closes late (at least 3am but as I’ve never been there later than that so I can’t say). So if you want a place to boogie while not having to pay a door charge, it’s quite a good option.