They are very much risk/reg in FS, and as most banks cant hire strong change managers for these projects for love nor money (no good ones anyway) they rely heavily on consultants and contractors to do the heavy lifting.
they have about 50 people in London currently I think, so somewhere between the two you have your recruitment process i.e. huge client demand, but small sales community to win it, cant carry a bench, so need to hire fast, cant staff rubbish out so retract a little.
I reckon its 2 - 3 interviews, one of which will be phone based and quick decisions.
But I'm just guessing.