IMDB entry:

The group was composed of three brothers who first performed together professionally in the 1950s on the children’s television show All Your Own.^[1] Initially performing as The King Three, they appeared on the BBC Television early in their career on Six-Five Special,^[2] and by 1957 had been named “top vocal group” in the reader’s poll of NME.^[1] Their first hiton the UK Singles Chart was their cover of “A White Sport Coat“, which hit #6 in 1957. In October 1960, they were again voted “top vocal group” in the NME reader’s poll.^[3] They had a string of successful singles through 1961, after which time they continued recording but found their popularity waning.

Group leader Denis King later became an award-winning composer for television, film, and musicals; among other things, he wrote the theme music for The Adventures of Black Beauty and Lovejoy.