GUEST,SB666 The American version came first . “This Is Your Life is a British biographical television documentary, based on the 1952 American show of the same title” . Wiki

The theme music 'Gala Performance' was indeed composed by Laurie Johnson. Anyone still looking to surprise their partners can find Gala Performance here:
https://www.youtube.com/watch?v=a8SZdTCEjZw