John Gilbert was a long-term supporter of animal welfare causes. Whilst in the Ministry of Defence in charge of procurement, he insisted that the department find alternatives to sperm whale oil which had been used to tan ceremonial gloves for, among others, the Horse Guards. The MoD's insistence that there was no alternative to this product had become an obstacle to UK support for an import ban on whale products and an end to commercial whaling.
John's contribution to the success of both of those achievements was significant. He famously spoke at an anti-whaling rally in Trafalgar Square and, by sheer coincidence, the Red Arrows flew past during his speech. John, with his usual savoir-faire, paused long enough to look as if it had been part of his presentation.
He made himself particularly unpopular with Canadian diplomats with his outspoken condemnation of the commercial seal hunt that takes place early each spring off the east coast of Canada. On being ennobled as Lord Gilbert, in 1997, he insisted on his robe being made with fake ermine.