The ruler of Dubai, Sheikh Mohammed bin Rashid Al Maktoum, and his son, Prince Hamdan bin Mohammed Al Maktoum, were in London this week. The pair are known for their opulent lifestyles, and the prince's Twitter feed is a reliable source of photos of the family playing polo, attending important meetings and wearing fancy suits.
So when he posted a picture of their London trip, I assumed it would be pretty swish: inside Buckingham Palace, say, or on that funny moving walkway in front of the jewels at the Tower of London.
But no: it was a casual shot of the two taken aboard the London Underground.
Yes, the Tube is a great way to bypass London's gridlock, but as a world leader the Sheikh must know it's harder to stay safe in a tube carriage than an armoured car, or even a taxi. It's also, as you may have noticed, extremely hot on the Tube at the moment. So why did they do it? Because the Tube has somehow become an actual tourist attraction? Or were they hoping it would make them look like men of the people?
Whatever the reason, they aren't the only ones. Below are a whole load of celebrities for whom travelling by Tube can't be entirely practical, but who decided to do so anyway.
Jay-Z, Chris Martin, and Timbaland
...travelled to a gig at the O2 by Tube in 2013. Given the trio were apparently surrounded by an entourage of 10, this was probably not an off-the-cuff visit. (The photo evidence sadly disappeared from this tweet, but the BBC has a copy of it here.)
Oscar-winning actor Eddie actually takes the Tube all the time, implying it's not just a bid for good PR. Unlike most of the other entries on the list, he does not seem to bring his own photographer along.
K-Mid visited Baker Street station to mark the London Underground's 150th birthday with the Queen, Prince Philip, and approximately no normal passengers. She looked incredibly out-of-place the whole time:
Just a normal gal, hanging out on the Tube with a small bouquet and a fascinator.
Rihanna travelled to a 2011 London gig by Tube, with minimal fuss. No, really – there were only a few news crews there, filming the whole thing.
Ex-Prime Minister David Cameron is often officially photographed on the Tube. and no one around him ever seems to notice or care. Perhaps frustrated that he wasn't being adequately praised for his brave descent to the level of us normal folk, in 2015 he had a go at driving one instead.
George Osborne looks on stonily and then comments: "This is a great bit of kit."
Image: via Twitter.
Harry seems to have ditched his usual array of bodyguards for this picture. Is it a lookalike? Or is his entourage lurking just out of shot?
Kim K's younger sister showed her authentic, Kendall-from-the-block side when she visited the Underground on a recent London trip. You can just how down-to-earth she is by viewing the full video of her journey, "Moves on the Tube", available if you pay her website's very reasonable $2.99 monthly subscription fee.