The Pel debate has been given new impetus by the case of Sean Toye, landlord of The Fleece pub, Southwark, who was prosecuted for running a karaoke evening on the grounds that more than two people "performed" in one night.
He appealed against the decision and won, saying that as no more than two people were performing at any one time he was not breaking the law.
His lawyer, Anthony Lyons of Addleshaw Booth & Co, said: "This case sets an important precedent and clarifies the ambiguous 'two performer rule' which is outdated and interpreted in different ways by different licensing authorities."
Westminster council defends the Pel system, claiming that in its absence pubs could blast out music as loud as they liked all day and night.
Carl Powell, director of planning, said it was an "anomaly" that pubs could broadcast football matches without a licence, but said: "Because some offensive activities happen it is no reason to let other offensive activities happen."