Admit women or we quit, Sting and Stephen Fry tell Garrick

In letter ahead of vote, signatories including Mark Knopfler say relations with female colleagues have been damaged

The musicians Sting and Mark Knopfler have co-signed a letter with leading theatre producers and actors, warning that they will be obliged to resign their memberships of the men-only Garrick Club if members refuse to approve a decision to admit women in a vote next Tuesday.

The letter, seen by the Guardian, was also signed by the actor Stephen Fry, the West End and Broadway theatre producer Karl Sydow, and Matthew Byam Shaw, an executive producer on The Crown television series and co-founder of Playful West End theatre production company.