Middleton was pictured stalking deer on the 50,000-acre estate in Aberdeenshire, next to Prince Charles, a move that is the clearest sign yet that she will one day become his daughter-in-law.

However, Kate’s outing has been slammed by anti-blood sports campaign group People for Ethical Treatment of Animals (PETA), who say that the 25-year-old should not have been involved in the shoot.

“It is shocking and abhorrent that she is engaging in blood sports. Kate is obviously trying to endear herself to the Royal Family and her decision will do her no favours whatsoever,” the Daily Mail quoted a spokesman for PETA, as saying.

It is not clear whether Kate, dressed in camouflage gear, bagged her first ‘kill’. But she was photographed practising with a formidable bolt-action hunting rifle watched by Prince Charles and two ghillies before heading off into Highlands.

“Killing deer for a sport is a horrible pastime. It’s very sad that she has chosen to participate in this cruel sport. It’s hardly a setting a good role model for young women, killing animals and I can’t see that this will do her reputation any good whatsoever,” a spokesman for the League Against Cruel Sports said.

Seconding the opinion, Yvonne Taylor of PETA added: “Kate is obviously trying to endear herself to the Royal Family, which is absolutely appalling. It wasn’t so long ago when she was pictured wearing a fur hat which caused a public outcry and now she is endorsing blood sports. The vast majority of the public will be disgusted by these images.”

Meanwhile, the same excursion has made royal watchers speculate that Kate may soon become engaged to Prince William.

“This is a hugely significant step for Wills and Kate’s relationship. This visit indicates how Kate is fully integrated into the royal way of life. But more importantly it shows Prince Charles and Camilla fully accept her,” a royal source said.

William and Kate are spending a long weekend at Birkhall, Prince Charles’s home on the Scottish estate, which he took over five years ago when the Queen Mother died.

The couple are the guests of Prince Charles and the Duchess of Cornwall - thereby fuelling speculation of a possible engagement. (ANI)

Prince William