Originally, Fairchild was to meet a Dalek saucer descending on Westminster, before being exterminated. Jack Harkness, at Torchwood 3 in Cardiff would have urged the Prime Minister not to do it. The scene was dropped at an early draft, partly for time but partly because Russell T Davies thought the Daleks wouldn't be "so diplomatic".
The Prime Ministers are listed in rough chronological order by their first term in office. Please note that this template only uses information from fictional sources. Real world information should not enter into this.