Why William and Kate are Osborne’s new best friends...

THE best-kept secret in British diplomacy is out – the Duke and Duchess of Cambridge’s impending tour of India next spring, with Prince George and baby Charlotte in tow, adding infant star power to royal glamour. The visit is, I hear, part of what is being dubbed the ‘prince-and-pols offensive’, conjoining the monarchy and top ministers in wooing emerging economies.

Part of the plan is to promote the Prince to the forefront of major foreign royal tours. That has helped forge what one Palace source calls a ‘practical, tactical’ friendship between William and the Chancellor, George Osborne.

The two men get along well. From a stiff early meeting at the Royal Wedding, a joint interest in the Asia push has given them a subject to share insights and gossip about – most recently at the banquet for the Chinese leader Xi Jinping.

News of the trip was carefully timed to crown the visit to Britain this week of India’s popular new leader Narendra Modi, after what one No 10 source calls a ‘personal courtship’ by David Cameron. India is particularly sensitive about China’s rise and perceived kowtowing by the British Establishment.

The Indian leader, a celibate former tea-seller, was received at Chequers in a style markedly different from the formal banquet hosted for Xi. An India-themed vegetarian feast was rustled up (the equivalent of friends staying in for a curry night, jokes a No10 insider).

Crucially, Modi was entrusted with detailed briefings of British actions against Isis and Islamic extremism – which turned out to be horribly relevant after the attacks in Paris on Friday.

IUNDERSTAND the PM was assured that the guntoting carnage in Paris is deemed unlikely to recur here. Weapons are transported more easily across Europe’s open land borders than into the UK, and there has been concerted Islamist recruitment on Paris’s grim housing estates.

But the fresh assaults by fanatics, as well as blood lust in the wake of the fatal drone strike on Jihadi John, are causing ‘severe worries’ about UK threat levels, with weekend leave cancelled for counter-terrorist squads.

That is where the new genera- tion of royals comes in. Because now, more than ever, democracies under attack from an ideology dedicated to their destruction need to display self-confidence.

A former ambassador notes that deploying royal firepower on the Indian visit is a useful part of that mission. ‘The royals are Britain’s trump cards and William and Kate are the Ace’.

In the diplomatic game of thrones, Britain has stiff competition from Germany, which has worked hard to strengthen ties with India. Angela Merkel has just returned from a successful visit, which resulted in a deal to ‘fast track’ joint-ventures and help German firms link up with Indian tech companies. The Chancellor’s staff, I gather, will work with the Duke’s team to enhance Anglo-Indian partnerships.

One historic image, however, looms large over the jaunt, with personal significance for William – that iconic photograph of the late Princess Diana sitting alone on a bench at the Taj Mahal on a royal visit in 1992. The image of unhappy solitude confirmed rumours that the Waleses’ marriage was in trouble. One of those involved in planning the upcoming visit says William and Kate will most likely call at the site, and that the Duke is ‘not squeamish’ about the symbolism.

But a thorny issue still remains. Modi is currently in favour in London, but has a chequered past at home. In 2003, as a pro-Hindu chief minister in Gujarat, he was accused of allowing or even abetting an anti-Muslim pogrom that killed hundreds. That’s one destination off limits for the royals, for fear of stoking Muslim resentment in India and at home in these ever more sensitive times.