See what it says on the joining instructions, but short of turning up in white tie or a morning suit, it is always better to be over-dressed rather than under-. Besides the perception, it's usually easier to take it down a notch (tie off, jacket off etc) if you turn up and have pitched it wrong - I don't know what you'd do to smarten up a more casual outfit.No P Diddy stuff. No shiny suits. No brown or green ones, nor anything more unusual. No funny lapels.Stuff is always pressed. Forget than unironed exists.