I would say the only sure way to know is to email Hilton and ask. That's what I would do if booking outside the UK, for instance. It may also be worthwhile checking if your organisation has a 'corporate' booking code as well.

My experience is with a UK government ID, and have not been asked for it (or travel orders) in at least the last four UK stays booked under this rate including one in London this weekend. Always have ID with me, though!