Prince William and Kate Middleton down the aisle at last

PRINCE William finally walked Kate Middleton down the aisle at a wedding yesterday-but it could be TWO YEARS before they do it at their own.

The couple happily posed for photos at a friend's big day in Austria-the first wedding they have attended as a couple for nearly three years.

Click here to see photos of Prince William and Kate Middleton

Wills, who let Kate attend two Royal weddings ALONE this year, is usually careful they are only snapped together on an occasional night out or at polo.

But yesterday he didn't care who saw him tenderly place his hand on her shoulder moments before they walked into the church together.

And significantly he asked that his dad's bodyguard Dominic Ryan be Kate's for the day. SAS-trained Ryan is seen as the ideal candidate to act as her official protection officer if she gets engaged to the heir to the throne.

But last night a senior Royal Household source insisted any Royal wedding talk was premature. He told News of the World: "There is a lot of planning involved in a royal engagement announcement of a member of the family as senior as Prince William.

Engagement

"A number of high-profile people have to be informed formally, and the couple have to be introduced to the Prime Minister of the day among others. All this takes time.

"As far as I am aware I cannot see there being an engagement between the Prince and Miss Middleton for at least 18 months."

He dismissed rumours-which fuelled speculation of an imminent announcement-that the couple were set to meet PM Gordon Brown at Balmoral this weekend.

Yesterday Kate, wearing a sexy knee- length dress and fitted jacket, was full of smiles next to Wills at the Salzburg wedding of pal Chiara Hunt-sister of Olivia Hunt who went to St Andrew's University with them.

Singer James Blunt and TV presenter Ben Fogle, who is married to the bride's other sister Marina, were also guests.