Popular beat combo as a synonym for "pop group" is a cliché

Cliché

A cliché or cliche is an expression, idea, or element of an artistic work which has been overused to the point of losing its original meaning or effect, especially when at some earlier time it was considered meaningful or novel. In phraseology, the term has taken on a more technical meaning,...

 phrase

Phrase

In everyday speech, a phrase may refer to any group of words. In linguistics, a phrase is a group of words which form a constituent and so function as a single unit in the syntax of a sentence. A phrase is lower on the grammatical hierarchy than a clause....

 within British culture. It may also be used more specifically to refer to The Beatles

The Beatles

The Beatles were an English rock band, active throughout the 1960s and one of the most commercially successful and critically acclaimed acts in the history of popular music. Formed in Liverpool, by 1962 the group consisted of John Lennon , Paul McCartney , George Harrison and Ringo Starr...

, or other purveyors of Beat music

Beat music

Beat music, British beat, or Merseybeat is a pop and rock music genre that developed in the United Kingdom in the early 1960s. Beat music is a fusion of rock and roll, doo wop, skiffle, R&B and soul...

.

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

BBC

The British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff...

 panel game Have I Got News For You

Have I Got News for You

Have I Got News for You is a British television panel show produced by Hat Trick Productions for the BBC. It is based loosely on the BBC Radio 4 show The News Quiz, and has been broadcast since 1990, currently the BBC's longest-ever running television panel show...

, making fun of Ian Hislop

Ian Hislop

Ian David Hislop is a British journalist, satirist, comedian, writer, broadcaster and editor of the satirical magazine Private Eye...

's supposed lack of knowledge about modern music.

Derivation

It is widely held that the phrase "popular beat combo" was coined in an English courtroom in the 1960s by a barrister in response to a judge's query (for the benefit of the court's records) as to who "The Beatles" were; the answer being "I believe they are a popular beat combo, m'lud." However, this attribution has never been verified, and remains the stuff of urban legend

Urban legend

An urban legend, urban myth, urban tale, or contemporary legend, is a form of modern folklore consisting of stories that may or may not have been believed by their tellers to be true...

, despite the efforts of Marcel Berlins

Marcel Berlins

Marcel Berlins is a lawyer, legal commentator, broadcaster, and columnist. He writes for British newspapers The Guardian and The Times, presented BBC Radio 4's legal programme Law in Action for 15 years and is currently a Visiting Professor at City University London in the department.He was born...

, legal correspondent for The Guardian

The Guardian

The Guardian, formerly known as The Manchester Guardian , is a British national daily newspaper in the Berliner format...

newspaper, to track it down.

The phrase may have been influenced by events in the 1960 obscenity trial of Lady Chatterley's Lover

Lady Chatterley's Lover

Lady Chatterley's Lover is a novel by D. H. Lawrence, first published in 1928. The first edition was printed privately in Florence, Italy with assistance from Pino Orioli; it could not be published openly in the United Kingdom until 1960...

in which the legal profession was ridiculed for being out of touch with changing social norms when the chief prosecutor, Mervyn Griffith-Jones

Mervyn Griffith-Jones

John Mervyn Guthrie Griffith-Jones, CBE MC QC was a British judge and former barrister. He is most famous for leading the prosecution of Penguin Books in the obscenity trial in 1960 following the publication of D. H. Lawrence's Lady Chatterley's Lover...

, asked jurors to consider if it were the kind of book "you would wish your wife or servants to read".