BP has once again been put firmly in the frame when it comes to environmental activism.

An open letter from 78 artists to Nicholas Cullinan, director of London’s National Portrait Gallery, has called on the institution to end its decades-long sponsorship deal with the UK oil major.

Ahead of the announcement of this year’s BP Portrait Award winner, the artists called on the gallery not to renew the sponsorship deal when it expires in 2022 and urged it to look for alternative funding for the award.