Wiktionary
popular beat combo
n. (context UK ironic English) pop group
Wikipedia
Popular beat combo
Popular beat combo as a synonym for "pop group" is a cliché phrase within British culture. It may also be used more specifically to refer to The Beatles, or other purveyors of beat music.
The deliberately out-dated phrase may be used as a tongue-in-cheek synonym, or by someone to denigrate a pop group referred to, or may be used of another person's views to imply that they are "out of touch". It may also be used to ridicule legalese and antiquated courtroom practices.
The phrase is frequently used in the BBC panel game Have I Got News For You, making fun of Ian Hislop's supposed lack of knowledge about modern music.