How much flexibility to work from home regularly is there is in Big4 financial services advisory? And how many days a week would one expect to be visiting various client sites?My current in-house regulatory job is 9-6 at my desk 5 days a week and I am wondering whether a move to advisory might inject a bit of variety / flexibility (notwithstanding that the work may be more intensive).

It varies, a lot. It's mostly dependent on the team, and your partner.For example in my big 4 firm (FS Advisory) our partners and directors are extremely focused on ensuring we have a strong work/life balance and flexible working is part of that. I can generally spend any day I'm not on a client site working from home, and pretty much always do (besides team meetings/drinks/expenses to submit/just wanting to show my face to colleagues/friends). I know of other teams whereby working from home is simply not allowed because the senior management have the old fashioned "if we can't see you, you're not doing work" mentality.May help that I work outside of London in this regard though.