I knew of one bloke getting one of these in HK, I am pretty sure it allowed just one trip to the UK and was about £120.. I might be wrong, it was a passport with a white cover and one or two pages..
They were young kids, very polite and actually decent level of English, they checked my docs and passport about 5 times. Like they were petrified of getting something wrong. There was an American guy at the next counter getting involved in a heated debate as he didn't have onwards flight proof.