Former prime minister John Howard has joined an exclusive group of 24 living people to be honoured by the Queen with the Order of Merit.

Mr Howard was presented with the medal by Queen Elizabeth at Buckingham Palace overnight, with his wife Janette observing the ceremony.

Earlier this year Mr Howard was hand-picked by the Queen to receive the insignia of a member of the Order of Merit, in recognition of his distinguished service.

After being invested with the honour, Mr Howard said the Queen was a woman of commitment, duty and professionalism with a great sense of humour and an ability to embrace change, whose efforts are unlikely to be matched by a future monarch.

Mr Howard, 72, and his wife Janette, will be on the River Thames on Sunday for the Diamond Jubilee Pageant, the centrepiece of events planned to mark the Queen's 60-year reign.

"She is obviously quite touched - 'chuffed' I think is the word - by the genuine spontaneity which has grown, of interest not only in the weekend but in the Diamond Jubilee," Mr Howard said of the Queen.

"She's obviously stimulated by it and I believe that she will enjoy it. She deserves it."

Mr Howard met with the Queen on numerous occasions during his term in office from 1996 to 2007.

"She never fails but to do her job to the best of her ability ... she does it very professionally and she does it uncomplainingly and in a very friendly manner. She's got a great sense of humour," he said of the Queen.

"It's hard to think anybody will be there as long and do it so consistently and effectively. She is a woman of remarkable commitment to duty."

During Australia's 1999 republican referendum, Mr Howard - who admitted being "delighted" with the poll result - said the Queen maintained a professional approach towards Australia.

"From an Australian perspective she does have a very genuine interest in Australia. There's nothing feigned about her interest in our country and that's important to understand," he said.

He further applauded the Queen's ability to adapt since she became monarch aged 25.

"The fact that she was able to decide the sort of things that she was able to let go, but to have the intelligence to understand the things that were important for the continuity of the office, were a tribute to her intelligence as well as her sense of duty," Mr Howard said.

Former PM John Howard joins Queen's 24