With weeks to go until the birth of his first child, Prince William will soon be staying up to the early hours for an entirely different reason, but before he swaps nights out for nappies, the father-to-be headed out with his brother Prince Harry to party in London.
The royal pair were spotted emerging from Tonteria nightclub in Sloane Square, where they had spent five hours with friends celebrating at the stag do of one of their closest friends.
The Duke, 30, wearing a bright orange Greys cap emblazoned with the words "Born to fish" and a Helly Hansen fleece, kept his head down as the group left the club through a back door at 1.15 am.
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His younger brother, 28, who was dressed in an open-necked shirt, smiled as he followed him out.
According to the Telegraph, William and Harry were attending the stag do of Thomas van Straubenzee, who is due to marry Lady Melissa Percy, the youngest daughter of the Duke of Northumberland, later this year.
Thomas, a chartered surveyor, is one of Harry's oldest friends and the Prince was the person he called back in 2011 when he was mugged, prompting the royal to rush to his aid.
Interestingly, Harry's ex girlfriend Chelsy Davy is Lady Melissa's best friend, and is expected to be chief bridesmaid at their forthcoming nuptials.
Thomas is also very close to William — Thomas served as an usher at his wedding to Kate Middleton in 2012, and the pair visited New Zealand together during their gap years before attending university.
While it is not known when the nuptials will take place, there is a chance that Kate might be unable to attend given that she is due to give birth in the middle of July.
Tragically, Thomas' brother Henry, who was in Prince Harry's class at Ludgrove prep school, was killed in a car crash in 2002 when he was just 18. He had earned an Army scholarship and intended to follow a career in the military after a gap year working at a school in Uganda.
The Princes went on to become patrons of a memorial fund set up in Henry's honour, and have attended several fundraising events.