A North-East psychologist said last night that the statement by Prince William and Prince Harry welcoming their father's engagement was very encouraging.

But Dr Alan Bradley warned there could still be problems ahead.

William, 22, and Harry, 20, said: "We are both very happy for our father and Camilla and we wish them all the luck in the future."

Dr Bradley, a Stockton-based consultant clinical psychologist who specialises in helping parents and children survive divorce, said: "The fact that the boys are publicly supporting the marriage says something.

"If we take it at face value, it is incredibly encouraging."

Dr Bradley, 57, is well aware of the pain of divorce, having watched his parents break up during the 1950s and gone through the collapse of his own marriage.

"What we have to take into account is the fact that Mrs Parker Bowles will be their father's wife, but that doesn't make her their mother," he said. "My understanding is that these boys loved their mother very much. It always appeared that they were physically very close to one another.

"They will have a very different relationship with their new stepmother, which is perfectly understandable.

"Mrs Parker-Bowles can now play a very valuable role in the princes' lives as their father's wife, and supportive adult family member.

"It appears to me that the marriage is formalising a pre-existing arrangement. The boys know Camilla really well. She has been part of their life for some."

However, Dr Bradley said the arrangement was not without danger.

"There will still be a lot of very strong emotion flying around and if Mrs Parker-Bowles suddenly wanted to become their mother, rather than their father's new wife, she would find herself in deep water."