* Sadiq Khan called on to end permission for oil branding of Royal Opera House’s ‘BP Big Screen’ broadcasts
* 200 signatories to letter include leading figures from classical, folk and popular music
* News comes day after BP Portrait Award judge and respected artists denounce BP sponsorship of the prize
* Extinction Rebellion group plans to mount protest this evening at first BP Big Screen of
Unofficial tour guides and hundreds of attendees descended on the British Museum yesterday, urging it to repatriate objects acquired through colonialism and end its long-standing partnership with the oil giant BP. Museum galleries were packed with people listening to rebel museum talks, and some routes through the museum were temporarily closed by security in response to the crowds.