So William and Kate are back from their stateside jaunt but one group of children will be forever transformed by their visit.

For when they dropped in to a child development centre in New York, the kids apparently believed that they had been chatting to Princess Elsa from the 2013 film Frozen.

Whether you're a king or a serf, mistaken identity is a common affliction it seems.

I cannot tell the difference between screen beauties Keira Knightley and Natalie Portman and have you actually ever seen Glenn Close in the same room as Meryl Streep?

The similarity between Bilbo Baggins actor Elijah Wood and Daniel Radcliffe of Harry Potter fame is uncanny for a pair who apparently do not share a gene pool.

On a recent visit to the UK Seth McFarlane, creator of American comedies such as Family Guy, spoke about how he is constantly mistaken for Donny Osmond over here. "I think it's the teeth and the sunny demeanour" he said.

I've been told I took like various people including the TV medic Dr Bramwell, as played by Jemma Redgrave (this was by my own parents, incredibly, although I had been overseas for a year when they made the observation, so perhaps they had in fact forgotten what I looked like). I was also told I was the spit of Drew Barrymore (she's blonde! but I kind of get what you mean with the chin thing) and also Penelope Keith during the "Margo" years, which is just ridiculous. That kaftan was a one-off experiment.

It's a risky business, telling people who they look like. As a culture, we are clearly becoming obsessed with how others view us, how else do you account for people posting a stream of photos of themselves online. But while we might look in the mirror and see our strong jawline others can't see past the over-sized nose.

I once told an acquaintance that he was the double of a soap opera character. Turns out I was like the 327th person to make the observation and it was not a welcome one.

I had no idea my casual comment would cause such dismay, but I suspect he felt he was far more attractive than the actor in question.

Social media has created new potential for mistaken identity. When Robin Williams passed away some took to the web to express sadness at the passing of singer Robbie Williams.

As for poor, long-suffering John Lewis of Virginia. The computer science professor receives the constant stream of comments on his customer service and critiques of his latest advert with good grace. This must be a particularly trying season for him.