There's no "P" involvement, it's simply a matter of money, no more, no less. The MOD is flat broke and cannot afford to support what it's already got, never mind running museums. In these recession-ridden times there's precious little private money around either. Most people fail to realise that obtaining ships, aircraft or tanks is the easy part, paying for the continued upkeep is the difficult bit. How many museums have you been round recently that look as they could do with a substantial cash injection? Most millennium-funded ones I've seen are looking decidedly shabby these days.
Andy