Ohka
The Telegraph article says: 'The aircraft... was one of just four brought back to Britain from the Far East to display in museums. It is not known what ever happened to the other three...'
I'm sure I remember seeing one dangling from the ceiling in the Science Museum. Perhaps a bit too unsettling (or genuinely educational) for modern sensibilities and removed, along with that whole floor devoted to the Port of London in the '60's...
Er, sorry for the thread drift. I see no reason why the UK shouldn't have a Head of State aircraft, especially if using the Voyager really does save money over leasing.