In an announcement this morning, BP said it was reviewing “its partnerships and initiatives to ensure activity is aligned to its new strategy”, adding it was looking for “new ways to best use its talent, experience and resources”.

Louise Kingham, senior vice-president for Europe at BP, said: “We are immensely proud of our role in championing British arts and culture for over 30 years, but the BP of today is a very different company from when we first started our partnership with the National Portrait Gallery.

“As we transition to become net-zero by 2050 and help the world get there too, we must look at new ways to best use our talent, experience, and resources.”

BP remains a sponsor of the British Museum and the Royal Opera House, although its 26-year sponsorship with the Tate gallery ended in 2016.

Mr Cullinan said: “The Gallery is hugely grateful to BP for its long-term support of the BP Portrait Award.

“Its funding for the Award has fostered creativity, encouraged portrait painting for over 30 years and given a platform to artists from around the world, as well as providing inspiration and enjoyment for audiences across the UK.”