All but one of the Queen’s nine prime ministers before Mr Blair were made Knights of the Garter, an honour created by Edward III in 1348.

Sir Tony’s 14 year wait to be made a Knight Garter since leaving No 10 is the second longest for any former prime minister, topped only by Edward Heath who was not made a Garter Knight until 1992, 18 years after standing down as PM.

While Sir John received his invitation to become a Garter Knight in 2005, eight years after leaving Downing Street, Margaret Thatcher waited five years, James Callaghan had an eight year wait and Harold Wilson was admitted to the Garter immediately upon leaving office.

Other ex-PMs could now be honoured

The award for Sir Tony could mean that other ex-PMs like Gordon Brown and David Cameron will now be similarly honoured by the Queen.

Boris Johnson’s predecessor Theresa May has taken to styling herself “Lady May” in her private life because her husband Philip was knighted in October for supporting her as PM when she was in Downing Street.

Sir Tony issued a statement on Friday, speaking of his pride at his honour. He said: “It is an immense honour to be appointed Knight Companion of the Most Noble Order of the Garter, and I am deeply grateful to Her Majesty the Queen.

“It was a great privilege to serve as Prime Minister and I would like to thank all those who served alongside me, in politics, public service and all parts of our society, for their dedication and commitment to our country.”

Also joining the Order of the Garter is Baroness Amos, the former Cabinet minister in Sir Tony’s government who becomes a Lady Companion of the Order, the first person of colour to be appointed.

The new appointments take the total number of Knights and Ladies Companion to 21, of a maximum 24. Baroness Thatcher was admitted in 1995 and Sir John Major in 2005.