David Cameron will today hail the “steadfast” Queen – calling her a “rock of strength for our nation” as she celebrates her 90th birthday.
The prime minister will lead tributes in the Commons, followed by Labour leader Jeremy Corbyn and SNP Westminster leader Angus Robertson.
Backbench MPs will also have the chance to mark the occasion in the specially organised “humble address” – as will peers in the House of Lords.
Mr Cameron will say: “Her Majesty The Queen has lived through some extraordinary times in our world.
“From the Second World War to the rations with which she bought the material for her wedding dress.
“From presenting the World Cup to England at Wembley in 1966 to man landing on the moon three years later.
“From the end of the Cold War to peace in Northern Ireland.
“Throughout it all, as the sands of culture shift and the tides of politics ebb and flow, Her Majesty has been steadfast – a rock of strength for our nation, for our Commonwealth and on many occasions for the whole world.”
At yesterday’s PMQs he declared “long may she reign over us”, describing the occasion as an “important landmark”.
Staunch republican Mr Corbyn also said he was “looking forward” to wishing the Queen a happy birthday, prompting laughter from the Tory benches.
He was criticised last year for failing to sing the national anthem at a Battle of Britain memorial service and over whether he knelt in front of the monarch when he was sworn into the Privy Council.
A Labour source confirmed he would speak in the debate, which is expected to take up most of the day.
Her grandson Prince William has said of the Queen: “Time and again, quietly and modestly, the Queen has shown us all that we can confidently embrace the future without compromising the things that are important.”