Prime Minister Stephen Harper told the CBC's Peter Mansbridge Tuesday that it has been a "great experience" to be in London this week for the celebration of the Queen's Diamond Jubilee.

Harper's affection for this monarch is no secret.

Cameras were allowed to shoot only the opening moments of his otherwise private audience with the Queen at Buckingham Palace on Wednesday, but his genuine enthusiasm was on full display as he bowed and made small talk for the cameras.

And Harper shared with the Queen a personal note: that his parents started dating the day she began her now 60-year rule.

He also presented her with the flag that flew on the Peace Tower on Parliament Hill on the exact anniversary of the start of her reign.

The private audience was a prelude to the main ceremonial event of the day Wednesday: the unveiling of a new Jubilee portrait by Canadian artist Phil Richards. The artist, Gov. Gen. David Johnston and Canada's High Commissioner, Gordon Campbell, were all on hand as Harper invited the Queen to pull the cord for the big reveal.

The Canadian government commissioned the work to commemorate the Diamond Jubilee year. While it was unveiled in London Wednesday, it's eventual home will be at Rideau Hall in Ottawa.

The painting, done in acryllic on canvas, stands more than three metres high and towered over the Queen herself as she admired it for the first time.

The Queen was involved in consultations about the portrait during her tour of Canada in 2010. Background notes supplied by the prime minister's office say Richards had a private audience with the Queen and oversaw a series of photographs that were taken by photographer Michael Bedford.

Fittingly, a portrait of the Queen's great-great grandmother, Queen Victoria — the only other Canadian monarch to celebrate a Diamond Jubilee — hangs in the background.

Although she's portrayed standing in a doorway at Rideau Hall, the Queen apparently never posed for Richards, nor had she seen the finished work before the unveiling.

"It's changed quite a bit," the Queen told Richards, taking it all in while camera shutters flashed in front of the huge gold-framed image.

'No touching': PM

"Do you think you're going to have to rebuild Rideau Hall to put it in?" the Queen joked to the governor general.

"We'll find a spot," Johnston assured her.

At the unveiling, Johnston pointed out a specific detail on a chair in the painting.

"No touching, David," Harper said to the governor general, amid some laughter.

This work is only the third official portrait commissioned by the Canadian government. The two previous portraits were by Canadian artists Lilias Torrance Newton in 1957 and Jean-Paul Lemieux in 1979.

After a prompt from the Queen asking how the large portrait got to the Palace, Harper acknowledged "a number of people in the room here today were instrumental in having it brought here."

Those people included former Liberal foreign affairs minister Bill Graham, who helped with fundraising to pay for the transportation of the artwork to London.

The defence department transported the artwork through "previously scheduled flights." But the RCMP Foundation, a not-for-profit group, covered the costs associated with the ground transportation and its temporary presentations in London.

It has more travel in store: after its debut at Buckingham Palace, it makes the short trip over to Canada's high commission, for public display over the next week at Canada House. After that, it will be installed in its permanent home at the governor general's residence back in Ottawa.

Happy Beatles fan

During his private audience earlier, Harper also told the Queen he originally wasn't going to arrive in London with his family in time to attend Monday evening's tribute concert.

The prime minister said Camilla, the Duchess of Cornwall had persuaded him to arrive a day earlier to see it.

Prime Minister Stephen Harper had a private audience with Queen Elizabeth at Buckingham Palace on Wednesday. (Sean Kilpatrick/Canadian Press)

"I'm glad I did," Harper told the Queen.

Presumably, these powers of persuasion were used during her tour of Canada with the Prince of Wales only two weeks ago, when Harper had a chance to speak personally to them, too.

As a devoted fan of the Beatles, it's hard to imagine Harper passing up the opportunity to see Paul McCartney perform live.

Harper plays the piano and once surprised a gala audience at the National Arts Centre with a performance of the Beatles' song "A Little Help from My Friends." Since then, the media is occasionally tipped off about well-known artists joining in impromptu jam sessions at the prime minister's official residence in Ottawa.

Harper told reporters at a Christmas reception last winter that McCartney is the person with whom he'd most like to have a jam session.

However, the prime minister added that McCartney's unlikely to agree to join him, since Harper once declined to take the former Beatle's call when he was campaigning against the seal hunt on Canada's East Coast.

Harper said before his CBC interview on Tuesday that seeing McCartney in concert was a personal highlight. He'd never seen Sir Paul live before this week.