The Duke and Duchess of Cambridge
05/02/2011 at 01:30 PM EDT
Closer to dawn
than midnight, newlyweds the Duke
and Duchess of Cambridge
boogied down to the Beatles' "She Loves You" as friends joined them in a huge sing-along at the end of their special day. And then they had another
send-off – in a mini Fiat car.
The couple took to the dance floor at a special disco inside Buckingham Palace in front of their nearest and dearest. The grand room had been transformed with a curtain draped down that reflected the strobe lights. Their final dance was to the Beatles classic.
"William and Kate were in the middle, giving it their all. It wasn't as if they were going to leave everyone to it. They stayed to the last minute," a guest tells PEOPLE. "Everyone was singing and dancing and enjoying themselves so much."
Then, everyone was asked to go out to the fine lawns behind the palace. There, a little Fiat, a classic Cinquecento model, had been decked out in finery.
"It had balloons all over it and an open top," the guest says. "They squeezed into it, sat out on the roof, while one of the servants drove the car and drove off along the gravel paths. Then the fireworks went off. There were big ones, but it was only for two minutes."
The couple drove away, but didn't actually leave the premises.
Earlier, Prince Harry
had played master of ceremonies at the reception. He introduced the bride's father, Michael Middleton, then the groom, who gave a speech, and Tom van Straubenzee and James Meade – William's friends, who toasted the couple together.
Finally, Harry gave his own best-man speech. "He is naturally funny, and it was a great, private gathering of friends," the guest says.
Dinner included salmon with crab and langoustine from Lyme Bay, with Meursault wine. Then Highland lamb with vegetables form Highgrove. The dessert was ice cream, sherry trifle and a chocolate dish.
The music started with Ellie Goulding, who sang a few tracks, followed by the disco.
The couple were clearly thrilled. "They were in the full party spirit, as though they had done the pageantry and the formal bit," says the guest. "They really went for it and let their hair down."