I can't speak for the London office, but the bureau in Macclesfield became soul destroying. I worked there for over 3 years, first 2 were fantastic then the management changed, turnaround of about 60- 80 staff in the time I worked there which speaks for itself in an office that holds 60 members of staff.
No people management,
No bonuses (no matter what is promised)
The management will overwork you if your capable, I have seen the strongest of personalities break.