Personally, I don't see why everyone is up in arms about it (not just saying that because I'm a woman & bare bums are on show); everyone has to let their hair down once in a while, Harry just got caught out, if anything, bet his dear ol' granny is jealous that she didn't think of doing it before back in her younger days!
No one wants to see old lady boobs going south, right?

Like I said, Harry just got caught out, if he wasn't royalty, everyone would over look it, and get on with their lives, Harry's just getting bad mouthed by the paper's because he's royalty & has a 'status' to up hold. His brother got married to one of the fittest women on the planet, Harry's allowed some fun!
I'd like to high five the bloke to be honest!