Bank has been bigging up reductions in “operational emissions” while continuing to finance the fossil fuel industry.

But experts say these “abusive” lawsuits, which are designed to demoralize and drain resources from activists, should be fought, not feared.

Lord Frost is one of several departures from the Global Warming Policy Foundation, which has links to Tory leader Kemi Badenoch.

The decision to allow Novatek to attend the flagship conference was described as “disappointing” and “disturbing” by campaigners.