A BBC art historian has said art galleries prevent visitors taking phone photographs so they can sell more tea-towels and postcards, after he was told off for photographing an exhibit at the National Gallery in Scotland.

Dr Bendor Grosvenor, who was an art historian for Fake or Fortune, posted a picture of a waving hand obstructing his iPhone’s view of a Rembrandt painting, and wrote: “I'd love to be able to show you how excellent the new ⁦@NatGalleriesSco⁩ Rembrandt exhibition is. But at the merest hint of my iPhone, an assistant rushed over to say no photos allowed, and demand that I delete the photo I'd taken (of his hand).”

He told The Telegraph that the rules are in place for licensing reasons, so galleries can sell more merchandise.

The art writer explained: “What museums do is they try and raise the revenue by selling image licenses by reproducing their photos. If ordinary punters take photos then they think that stops their ability to do that. But someone taking a picture on their iPhone isn't going to start making up tea-towels.”

Dr Grosvenor argued that museums could be shooting themselves in the foot with this rule, because social media posts of paintings can drum up excitement for an exhibition.