Speculation continues to surround Sir Paul McCartney's wedding to Heather Mills, which is expected to take place in the next few days - with some even suspecting it has already taken place.

Sir Paul has been determined to keep the ceremony "as private as possible", but attention has focused on two possible venues - a mansion in Long Island, New York, and an Irish castle.

Sir Paul appeared at Monday's Buckingham Palace concert

Sir Paul was reported to have told friends and relatives to keep Thursday, 6 June free.

They were expected to be directed to the mansion owned by John Eastman, brother of Sir Paul's first wife Linda, in the affluent Hamptons, Long Island.

But one gossip columnist has given an alternative prediction - that the nuptials will take place in Ireland, at Castle Leslie in Co Monaghan, on Tuesday, 11 June.

One newspaper has even reported that the couple may have already held a secret ceremony.

The continued speculation comes after Mills watched from the royal box at Buckingham Palace as Sir Paul led a host of stars for the finale of the Queen's Golden Jubilee pop concert on Monday.

All Sir Paul will say is that he and Mills will marry "this summer", but the ceremony is expected to take place before his 60th birthday, on 18 June.

Mills sat next to London Mayor Ken Livingstone at the concert

There have also been rumours that the venue would be a secret location in England or Skibo Castle in Scotland - where Madonna and Guy Ritchie held their wedding reception.

Sir Paul's spokesman has insisted that even he does not know where the event would be held.

Reports have claimed guests are going to be led on a "marital mystery tour", not being told the exact location until the last minute.

The only other surviving Beatle, Ringo Starr, and Sir Paul's children Stella, Mary, James and Heather are expected to be among those present.

Sir Paul recently said he and Mills, were anxious to "get wed with a bit of privacy".

The ring: Reported to have been thrown out of hotel window

He was reported as saying he had chosen a best man and "done all the stuff a groom is supposed to do when he gets married".

When the couple announced their engagement in 2001, there was speculation that they would hold the ceremony in Sussex before taking a honeymoon in Jamaica.

But there have also been reports of rifts in the McCartney family and rows between the couple.

Some newspapers claimed Sir Paul threw Mills' engagement ring out of a hotel window and shouted that he wanted to call the wedding off.

Sir Paul met Mills, 34, an anti-landmine campaigner and former model, at a charity function in 1999.

He admitted that he was "a bit nervous" when he proposed during a short break in the Lake District.

The singer was married to Linda McCartney from 1969 until her death from cancer in 1998.