The Rolling Stones have joined the campaign to increase revenues from streaming to musicians in the U.K., adding their names to a letter for the Prime Minister that has so far received a non-committal response.

The Stones join Tom Jones, the Bee Gees’ Barry Gibb, Emeli Sandé, the estate of the late Joe Strummer, Alison Goldfrapp and Jarvis Cocker of Pulp as new signatories.

The letter, which was sent in April, wants Boris Johnson to update U.K. copyright law so that artists, performers and songwriters receive the same rights they have in radio, otherwise known as equitable remuneration. So far, it's received an “interested but non-committal reply,” according to NME.

The demand is a big ask that has little chance of happening, but insiders hope the campaign will result in some sort of positive change for a situation that many deem highly unfair, as revealed in the evidence sessions for the recent Government inquiry into the economics of streaming.

More than 150 artists have signed the open letter, including previously announced signees Paul McCartney, Bob Geldof, Annie Lennox, Lily Allen, Chris Martin and Kate Bush.