A pretty standard suit and collared long sleeve shirt look beloved of head office middle managers everywhere. Usually tie-less except when I'm travelling, visiting other service partners, regulators etc, or when I'm hosting someone. Then I tend to tart myself up a bit out of respect for whoever I'm meeting.
Friday is mufti day in the office. Still means collar and shoes, but you can be more casual. I wore a linen jacket the other week and got the piss ripped out of me, probably deserved it. Apparently I resembled something out of "death in paradise".