The Queen has declared 1926 - the year she was born - a vintage year as well-wishers turned out in their thousands to wish her a happy 90th birthday.

With the Duke of Edinburgh by her side, the Queen went on a walkabout in Windsor and received armfuls of cards, bouquets of flowers and even a cake as she acknowledged the greetings of the crowds.

The royal fans who lined crash barriers around the town centre broke into spontaneous renditions of Happy Birthday and applause as they caught sight of the monarch.

And when the Queen met a group of fellow nonagenarians - all born in 1926 - Rosamund Fulawaka, whose 90th birthday was on April 10, said she told them: "You were all born in a lovely vintage year."

There were a few famous faces among the crowds, from the Gogglebox stars Sandra and Sandy, to reality TV celebrity Joey Essex and television chef Mary Berry.

The event was part of an unveiling ceremony at the foot of Castle Hill in Windsor that formally marked the launch of the Queen's Walkway .

The walkway - a four-mile self-guided walking trail of Windsor by the Outdoor Trust - has been created in honour of the Queen becoming the country's longest reigning monarch.

Historian Hugo Vickers, the Outdoor Trust's chairman, helped the sovereign remove the cloth from a large temporary display board in the middle of a main road and she remarked it was a "lovely day".

Mr Vickers said: "She was terribly happy with the beautiful weather and the lovely occasion. She said it was a lovely day."

He added: "She loved the panel. Prince Philip said it wouldn't last long if we left it there."

When the Queen first emerged from her chauffeur-driven state Bentley, members of the public sang as the Band of the Coldstream Guards, in their red tunics and bearskin hats, played Happy Birthday.

The public added their own informality to the occasion, when some inserted the words "Happy Birthday dear Queenie" into the song.

When the rendition ended and the Queen began to walk past the crowds, some shouted out: "Happy birthday Your Majesty."

She was dressed in what was described by Buckingham Palace as a "spring grass green" wool and silk weave coat and dress with hat to match, adorned with flowers by her dressmaker Angela Kelly, for her birthday appearance on the sunny but chilly day.

On her shoulder was one of her favourite brooches, the Star diamond brooch.

At one point she stopped with lady-in-waiting Jennifer Gordon-Lennox to briefly chat to sisters Judy and Anne Daley, from Cardiff, who were each holding a balloon that formed the number 90.

The siblings had been featured on breakfast television earlier and in the excitement the number nine balloon had floated off over Windsor, but luckily another was donated by a local shop.

Anne, 55, said: "When the lady-in-waiting saw the balloons she said 'you've got the nine back'. The Queen was killing herself laughing, she must have seen it on TV, she was really lovely."

Judy, 50, a civilian police worker, said: "The Queen's just remarkable, a very formidable lady, and certainly the one we all look up to.

"She's remarkable for her age, and her dedication to duty, day in and day out - just a wonderful, wonderful lady.''

Gogglebox stars Sandra and Sandy had staked a spot in the crowd to get a good view of the Queen.

Sandra Martin, who was wearing a pair of Union flag glasses, said: "We've taken time out of filming to come here and stayed overnight in Windsor.

"We're here to celebrate the Queen's birthday and I'm the only one on the programme who is allowed to speak about the Queen - for the last 20 years I've been a loyal, devoted follower.''

Philip stopped to talk to the pair and Ms Martin said later: "He asked me what I do and where I live and I told him I'm Sandra, I live in Brixton and I appear on TV.

"I told him I sit on my sofa and watch TV and you watch me watching TV and that made him laugh."

Town crier Tony Appleton, 80, from Chelmsford, had been at the Lindo Wing when Prince George and Princess Charlotte were born.

And he had had a new uniform specially made for the occasion.

"I said to Her Majesty 'I introduced your two great-grandchildren to the world'.

"She laughed and said 'Oh, did you?'

"It's made my life! I had my uniform made specially today from royal tailor GD Golding. It's an amazing day."

David Cameron has led the tributes to the monarch - born on April 21 1926 - who has become the country's first nonagenarian sovereign.

The Prime Minister tweeted: "The whole country will want to wish the Queen a happy birthday today - she has been a rock of strength for our nation."

The Prince of Wales and the Duchess of Cornwall were married at Windsor's Guildhall and in its open-air portico, known as the Corn Market, the Queen and Philip chatted to a group, mostly women, who turn 90 this year.

Yetta Jacobs, who celebrated her 90th birthday on February 11, was evacuated to Windsor in 1939 from London's East End.

"I think she just said hello,'' she recalled after their meeting.

She added: "I told her I was evacuated to Windsor and she asked if I liked it and I said yes."

Rosamund Fulawka, from Ascot, who turned 90 on April 10, said: "The Queen said to me 'You were all born in a lovely vintage year'. That was a lovely thing to say.

"It was wonderful to meet her. I had seen her from a distance but never seen her close up so I had a really good look and thought she was just lovely."

Nadiya Hussain, winner of the BBC's The Great British Bake Off, had made the Queen an orange drizzle birthday cake over four days, and used 42 eggs to create the three-tier confection which actually featured 12 cakes.

She said: "My theory was if lemon drizzle was good enough for Mary Berry, we can change it up and do one for the Queen."

The baker added that she froze when she first spoke to the Queen but recovered: "She asked me about what was in the cake, because she said 'Does it cut?', so clearly she's had issues about cutting cake - hence why I didn't do a fruit cake."

She added: "You've got to feel some pressure when it's the Queen, right? Every time I tried to ignore the fact I was doing it for the Queen, my husband would very conveniently remind me - 'Hey, hey, you're slacking. It's for the Queen. Get up, you can't be lying down'."

And it appears the Duke may be an avid watcher of the BBC's hit baking show, Ms Hussain suggested.

"The Queen said 'Oh, she won the baking show' and he said 'Of course I know she won the baking show' - I think they were having a bit of a conversation."

A decade on from her 80th the Queejn used an open-top state review vehicle to complete the last part of her public appearance and she and Philip were driven through Windsor past the crowds.