Biographer Andrew Morton, in his 2011 book “William and Catherine”, writes about how William’s 1998 trip to Kenya sparked his passion.
Mr Morton writes: “His real love affair, in fact, was with Africa.
“The continent spoke to him, as it does to so many who visit it.”
At the time false rumours, spread that William had become secretly engaged to Ms Craig, when he visited her family’s game reserve near Mount Kenya.
However, William dismissed the rumours and has in fact called the Craigs his “second family”.
Ms Craig’s father, Ian Craig, said: “William just loves Africa, that’s clear.
“He did everything from rhino-spotting to anti-poaching patrols, to checking fences.”
The prince learned some basic Swahili, too, and became involved in the Craig’s elephant charity the Tusk Trust.
William would return to Africa in 1999, when he went on safari with Prince Harry and their nanny Tiggy Legge-Bourke.
The prince would also travel around the continent during his gap year, visiting South Africa, Botswana, Kenya, and cruising down the River Nile.
William even proposed in secret to Kate on holiday in Kenya in 2010 when, after visiting the Craig’s wildlife reserve, he took her on a trip to Lake Alice.
The prince surprised Kate by bringing out his mother’s engagement ring, which he had kept hidden in his backpack.
The newly-engaged royal pair did not break the happy news to anyone until their return to the UK, where they continued their holiday in Scotland before telling anyone about their secret.
The Duke of Cambridge’s love of the African continent is something he shares with his brother Prince Harry.
Harry set up his own charity Sentebale, alongside Prince Seeiso of Lesotho.
He famously took then-girlfriend Meghan Markle on a romantic trip to Botswana early in their relationship, and the engagement ring he presented the Duchess of Sussex with in 2017 features a Botswanan diamond as the central stone.
The Duke and Duchess of Sussex are even rumoured to be planning a move to an African country, as they are said to want be based there as representatives of the Commonwealth.
The Daily Mirror’s Royal Editor Russell Myers, speaking on podcast “Pod Save the Queen”, said: “It’s being talked about very seriously.
“Meghan’s the driving force behind it.”
However, Mr Myers also acknowledged the potential for the move to “cause big divisions within the Royal Family”.