The café occupies a bright and airy section of the library close to the Borough High Street entrance. There are long wooden communal tables, as well as smaller tables with comfier chairs. On both visits, Mouse Tail was heaving, with barely any free seats; it is a good place for lingering with a book or a laptop and has given the library a great buzzy vibe.
Mouse Tail's coffee vans generally only serve espresso-based drinks but the Borough café also serves single-origin pourovers (£3), brewed through the V60. The first time I visited, I tried a Kenyan coffee brewed as a pourover, which was fruity and refreshing — just what I needed to get me through a busy afternoon's coffee blogging. It was also really nice to see the barista introducing customers who weren't familiar with pourovers to the V60 technique. Welcome to the dark side!
The following week, I ordered a macchiato (£2), which was smooth and chocolatey with a hint of fruitiness, and which had a very good latte art heart. Mouse Tail's name comes from a term used by baristas to describe a perfectly extracted stream of espresso, and their espresso shots are rather good. The current espresso blend combines varieties from Brazil and El Salvador and I liked it a lot.
As well as the coffee menu, Mouse Tail also serves cakes, breakfast, brunch and lunch. The brunch menu looked great and was very reasonably priced so I'll have to go back to try it some time. The Borough branch is open 8–6 during the week, 9–4 on Saturdays and 9–3 on Sundays (the library itself is open a little longer so you can stay to finish your drink). They also have a small coffee bar on the Whitechapel Road, and the two vans are based at Canada Water and West India Quay, at present.
Mouse Tail Coffee. 211 Borough High Street, London, SE1 1JA (Tube: Borough). Website. Twitter.