There are two ways of seeing the extraordinary rise of Saudi Arabia’s Crown Prince: the blood-stained debut of a new dictator, or the long-overdue emergence of a reformer with the steel to take on the kingdom’s old guard. The British government is firmly in the second camp.

Mohammad bin Salman is just 32 years old, and his effective seizure of power means he defines the kingdom for a generation. He’s seen in Whitehall as a history maker, whose ruthless impatience might not only liberalise his country but create an alliance with Israel that could change the region.

Minsters talk about MbS (as he’s known in Whitehall) with admiration and awe. He recently laid on a trade fair, and the British delegation was amazed to hear a band playing upon arrival at the airport. They were then taken to a room where men were sitting next to unveiled women, with none of the usual intermission for prayers. ‘It was like we’d got off at the wrong country,’ says one official. MbS is talking about various investments: new cities built from scratch, a 30-mile bridge being built to the Egyptian resort of Sharm El Sheikh. Deepening alliances with several countries, Israel included. There is even hope, in Britain, that the Saudi-Israeli alliance could pave the way for an Israeli-Palestinian peace deal.

Dictators quite often make such noises to extract concessions from a gullible West. When Colonel Gaddafi disposed of chemical weapons that no one knew he had, Tony Blair flew off to Tripoli with businessmen offering trade, cash and military training. Gaddafi’s son Saif was hailed as a young leader at Davos. Libya carried on imprisoning and torturing opponents, and found out that the West doesn’t mind if you talk about reform.

But the calculation in Britain is that MbS is different. It’s thought that he’s motivated by consolidating his personal power and by economic concerns. The oil money is running out, and Saudi Arabia needs new sources of income. MbS has been heavily influenced by Mohammed bin Zayed, the 56-year-old Crown Prince of Abu Dhabi, who has acted as his mentor. He has shown how quickly an economy can develop if the reforms are right.

As one senior official puts it, ‘He’s pro-women, so he’ll have half the population on his side.’ Perhaps more: he’s a millennial, and likes to point out that 70 per cent of his fellow Saudis are under 30 years old. ‘So we will not waste 30 years of our lives dealing with extremist ideas,’ he said last week, ‘we will destroy them today.’ This is not the language of accommodation. And it’s almost inviting an Islamist backlash, in the nation that produced most of the 9/11 hijackers.

The Crown Prince is frank about the risks, saying his country’s youth bulge is a ‘double-edged sword’. Young Saudis, he said, can create a new Saudi Arabia if empowered ‘but if they go the other way, they will bring destruction’. By his own admission, it’s quite a gamble. But one which the British government, such as it is, fully supports.