The Hop Locker

Jezza says

The original location is in the thriving South Bank Centre Market behind the Royal Festival Hall. The beer range here is wall to wall quality with no compromises at all. There's also a second bar each summer, usually directly under the Hungerford Bridge right by the river, with an additional 12 draft beers. The summer bar normally opens from late April to end September, but check the HL twitter feed for details. Grab a bite to eat from one of the many excellent food stalls in the market, or from one of the neighbouring stalls on the riverside. Opening times given above are for the original bar. The summer bar is normally open from 12 noon 7 days a week.

Steve says

Located at the rear of the South Bank Food Market is this excellent beer stall. 9 beers on tap and a quality selection of packaged beers to take away. The joy of its location is that you can pair beers with whichever world food happens to take your fancy. 1/3 pint measures are available.