His ancestors may have spent a significant proportion of their time slaughtering African game for sport, but Prince William seemed determined to begin the process of trying to make up for that last night, when he showed a rarely seen side of his character as he gave an impassioned speech demanding protection for endangered big cats in the wild, after attending the premiere of the conservation movie, “African Cats” with Kate.

William, who had arrived earlier in torrential rain, and was pictured gallantly holding an umbrella over his wife who was dressed in a chic Matthew Williamson number, is patron of Tusk Trust, a conservation charity. The couple got engaged while on safari in Africa, and in 2001, he worked for six weeks on an African game reserve owned by the father of his ex-girlfriend Jecca Craig. He was recently said by aides to be ‘appalled’ at the slaughter of one of the rhinos there, Max, who was shot 15 times by poachers.

After watching the film, William said, referring to a popular British soap opera: “Wow, that was amazing. I’m emotionally exhausted. There’s more drama in that than EastEnders.”

The Prince went on: “African Cats shows graphically the battle for survival facing every lion and cheetah born in the wild. The natural challenges are formidable enough, without man’s interference. Loss of natural habitat, due to encroachment by human beings, is the principal reason that there are today around just 25,000 lions remaining in the African bush – 50 per cent less than 20 years ago.

“There could be as few as 12,000 cheetahs. The population distribution of these marvelous creatures is patchy too. Kenya, with around 2,000 lions, has as many as all of West and Central Africa put together. This uneven geographic spread further lowers the species’ chances of achieving stable populations and, therefore, longer term survival.

“The decline of big cats is, of course, of huge concern. But they’re not the only ones. Tusk and other conservation groups are now confronting the truly horrific situation effecting Africa’s elephant and rhinoceros. Both are being mercilessly and illegally poached at a rate not seen for decades. Unless this stops, these two majestic animals will be, in a few short years, but a memory in the wilds of Africa. This cannot happen. We must not let it.”