Look of love... Kate and her prince pose for Diana photographer

Two official photographs to mark Prince William's engagement to Kate Middleton show the couple "brimming with happiness".

The portraits, one formal and the other more casual, were taken by Mario Testino, the fashion and celebrity photographer, who created some of the most enduring images of Diana, Princess of Wales.

In the pictures William and Kate, both 28, look very much in love, holding each other in the setting of St James' Palace in London.

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The photographer said: "They are in their prime and brimming with happiness. I have never felt so much joy as when I see them together."

In the formal image, the couple Kate is wearing a white Reiss dress, Links earrings and her engagement ring that once belonged to Diana. The prince is dressed in an outfit by Turnbull and Asser.

They are standing in the palace's council chamber with its walls hung with paintings of some of William's ancestors.

Three portraits can be seen – William III and Mary II both by Sir Godfrey Kneller and Karl William Ferdinand, Duke of Brunswick-Wolfenbuttel, by Johann Georg Ziesensis.

A second informal image shows the couple smiling and embracing, with William wrapping his arms around Kate.

Kate and William chose the two images to be released out of the set of pictures taken by the photographer.

On Saturday Home Secretary Theresa May denied claims royal security was being put at risk by coalition spending cuts.

But she said the Prince of Wales may have to abandon his historic Rolls-Royce in the wake of the attack by tuition fee protesters last Wednesday evening. Mrs May confirmed that the prince's wife Camilla had come into contact with the mob who surrounded the car in the West End.

Amid reports that Metropolitan Police Commissioner Sir Paul Stephenson offered to resign after the chaotic scenes, Mrs May insisted she had not considered falling on her sword.

She also defended the "robust" police response to the disorder in the capital.

"The Met Police obviously have to look at how they should be dealing with these demonstrations," she said.

"They will look across the board and they will be making operational decisions.

"What we need to do is find out what happened in this incident and to see whether there is anything that can be learnt from this incident."