All over the world yesterday, that photograph of three Queens in a line — one present, two future — will have been analysed with much fascination. It shows three generations of royalty all very comfortable with each other — especially the youngest who, less than a year ago, was a middle-class girl from Berkshire. The picture is eloquent testimony to the enthusiasm with which Kate Middleton has been welcomed into the royal fold. On the other hand, Kate radiates a self-assurance that comes from knowing the Royal Family have the kind of confidence in her that they never quite had in William’s mother. The palace is making huge efforts with Kate, refusing to make the same mistakes it did with Diana. Her progress as Duchess of Cambridge is being managed with huge care. There is astonishment in some royal circles that the Queen and Philip have chosen Kate to accompany them on a visit to Leicester on Thursday to launch the diamond jubilee tour of the country. Some expected her to take one of her grandchildren, such as Princess Beatrice or her sister Eugenie, who have expressed a deep desire to have a royal role. But the Queen’s private secretary Sir Christopher Geidt contacted Prince William’s private secretary Jamie Lowther-Pinkerton to say Her Majesty wanted Kate to go along. There could be no clearer indication that the Royals view the young Duchess as the vital ingredient in their future popularity. Indeed, William’s absence in the Falkland Islands, where he is on  secondment as a search and rescue helicopter pilot, was seen as the ideal moment for the Queen to step in. The concern is not about reining in Kate, but usefully occupying her,’ says an aide. ‘It was an opportunity to bring her more intimately into the palace machine.’ And it’s an opportunity to adjust certain other elements of Kate’s image. Surprisingly, you may think, there is ‘mild irritation’ about the media interest in her clothes, especially the references to her ‘thrift’ in being seen in inexpensive outfits — the ‘High Street Princess’. ‘There’s a danger in the Duchess being seen as always hunting out bargains,’ says a senior figure. ‘She is, after all, a royal princess and it’s not necessarily extravagant to dress like one.’ How starkly all this care and consideration compares with what happened to Diana when she arrived in the Royal Family. She was just 20, while Kate is 30. Diana was 12 years younger than Charles and with very different tastes, while Kate is a few months older than William and they share everything, even the shopping. No one was on hand to advise the young and inexperienced Diana. She had to learn royal protocol from scratch on the job. Being swept up by the Queen and Philip while her husband was away never happened to Diana. As a result, she trembled before engagements. She was visibly shaking when switching on the Regent Street Christmas lights, her first solo engagement in 1981. Diana had no guidance to speak of from Charles, other than when he expressed his irritation — for example, admonishing her when she put on a black dress for an evening function, saying that ‘black is for funerals’. Instead of encouragement from her husband, she bore the brunt of his envy when crowds flocked to her on their first foreign trip to Australia in 1983. To Charles’s chagrin, the crowds groaned when, instead of his glamorous wife, he approached them. William is totally different. He delights in his wife’s popularity. ‘He is so protective of her in everything they do,’ says an aide. One area of royal life with which Kate has still to come to terms is being addressed as ‘Your Royal Highness’ or ‘Ma’am’ and — worst of all — being curtsied to, especially by other royals. ‘She is rather embarrassed by all that stuff,’ says one old friend. ‘It’s one of the hardest things she is having to get used to.’ Some palace aides are uncomfortable with the inevitable comparisons made between Kate and Diana. For example, they regard as a big mistake Kate’s decision two months ago to wear a strapless black dress by Alexander McQueen because it was almost identical to a gown work by Diana 30 years ago. ‘The Diana factor is one that has to be watched,’ says a friend. ‘It does trouble the Royal Family.’ But there are aspects of Diana’s approach that seem to be encouraged, such as her involvement in charities and visits to sick children. It was while Kate was in Oxford last week and joined in a therapy session run by The Art Room charity of which she is a patron (she studied History of Art at St Andrews university) that she finally revealed the name of her cocker spaniel puppy, Lupo. Before that, Kate and William had insisted on keeping the name to themselves, to the consternation of palace aides who thought they were being ‘rather silly’. Was Kate’s decision to reveal the name instinctive — going along with William’s advice to be herself? Or was it part of a marketing campaign? We may never know, but it did make favourable headlines. For his part, the Prince of Wales has pointedly stepped back from having any involvement in coaching Kate or even a view on how she is performing and where she needs further guidance. Among old hands at the palace, this is seen as a deliberate policy so he will avoid any possible criticism for helping guide Kate when he failed abysmally to aid Diana. However, with some irony, he has quietly encouraged Camilla — by now something of an old hand in royal matters — to be ever available on the end of a phone to the Duchess of Cambridge. Significantly, Camilla took Kate to lunch at the Berkeley hotel in Knightsbridge shortly before the royal wedding. It was a jolly couple of hours with much laughter. Camilla also took Diana to lunch, of course, before her wedding, though this was a much less merry occasion. The then Mrs Parker Bowles seemed to Diana to be suspiciously curious in asking if she intended to go hunting with Charles. When Diana said she didn’t, Camilla (who did hunt with the Prince) noticeably relaxed. Charles is not completely without influence. William’s official expenditure — and therefore Kate’s — is funded by the Prince of Wales. This includes paying for Kate’s clothes. William’s office is said to be ‘always moaning’ that there isn’t quite enough money, a situation that would be exacerbated if Kate is forced by critical palace aides to abandon her taste in chain-store fashion. All in all, Kate is doing well as her first anniversary as a royal Duchess approaches. Indeed, who would have thought that when the Queen’s great anniversary arrived, she would have become Her Majesty’s most important Diamond Jubilee accessory.