Mark's is a great spot to be at. The room itself is gorgeously decorated with books lining the walls - it's impeccably clean and is a very nice space to be in. It's easy to get to from the tube, about 5 mns walk! Also on the ground floor (those of us with back and knee problems should choose here for ease of use).
Mark is very welcoming host - flexible, kind, accommodating - a cool person to know for sure! He's got a lot of information on Brixton and London that could help any travelers coming in.
Definitely would stay (and will) again!