The Queen endured a potential minefield of social tension today, as she celebrated her Jubilee with a lunch involving the surviving prime ministers of her reign.

Tony Blair and Gordon Brown, whose attacks on each other have only become worse since their time in power, were be joined by David Cameron, John Major and Nick Clegg.

Margaret Thatcher, who has largely retired from public life, was too ill to attend.

The guests ate salmon, roast duck breast with potatoes and seasonal vegetables and a trifle for dessert.

Cameron, Brown, Major and Clegg were joined by their wives, but Cherie Blair is not attending due to an ongoing legal case.

Her failure to join the lunch will fuel speculation about her fraught relationship with the Queen.

Alastair Campbell's diaries claim that Cherie Blair, who is thought to be a republican, once asked about an affair Queen Victoria allegedly had with her attendant, much to the annoyance of the monarch.

At least the Queen can relax in the knowledge Cherie wasl not attending this event. Far more problematic will have been the continued animosity between her husband and Brown. Their fraught relationship has not improved since they both left Downing Street.

Blair is actually far warmer to the current Conservative prime minister than he is to his one-time ally.

The peace envoy backed Cameron for 'chillaxing', saying it was vital "to have time out".

In his diaries, Blair described how he used alcohol as a crutch against stress and exhaustion towards the end of his time in Downing Street.

A similar dinner was organised for the golden jubilee in 2002, and attended by Blair, Thatcher, James Callaghan and Edward Heath.