11/20/2007 AT 12:35 PM EST
It was a night of royal revelry Saturday as the Princes William and Harry stepped out for a cousin's posh birthday party.
And although William brought along girlfriend Kate Middleton, Prince Harry
– who reportedly split
with girlfriend-of-three-years Chelsy Davy in mid-November – was noticeably date-free at the 30th Birthday celebration of Zara Phillips's brother Peter.
"Harry spent most of the evening with his male friends," says one guest at the 50-person bash, which began with dinner at the Cocoon restaurant. "There was no one else lined up to take Chelsy's place. It was Harry hanging out with the boys. He was very much steering clear of the ladies."
After the family-style, pan-Asian meal (washed down with plenty of Snow Queen vodka) the crew – including Princesses Eugenie and Beatrice – moved on to the private club Volstead, where they danced until 3 a.m.
"Everyone had a very good time," said the insider. "Lots of dancing, lots of fun. Everyone was up for a really great night out."