A bookshop's tweet about its "light-hearted" display of Prince Harry's memoir Spare next to Bella Mackie's book How to Kill Your Family has gone viral.

Bert's Books, in Old Town, set up the tongue in cheek display to mark the first day of sales of the prince's book in the UK on Tuesday.

A tweet capturing the display has since amassed almost 10,000 likes, more than 1,000 retweets and has been viewed one million times, at the time of writing.

READ MORE: No rush for Harry's memoir 'Spare' at independent book shop

Manager Alex Call, 35, said: "To be honest it was a light-hearted joke with the first customers of the day and to be fair Bella Mackie's book was already in our window.

"It was the best-selling book in our shop and we thought it would make everyone laugh and it has.

"Most people have taken it in the spirit it was intended but some people think we are being a bit mean about it."

People were seen queuing at bookshops this morning to get their hands on the first copies.

But Alex said there was no rush at his shop.

Alex said: "We have sold a couple but it is quiet in the shop - it always is on a Tuesday morning.

"I'm not expecting a rush but a couple of copies have been sold."

Many people took to social media to react to the display, after the team posted a photo on Twitter.

One person said: "Now I am going to spend all day thinking of other books to pair."

Another said: "Someone give them a prize for the best window display."

One user added: "This is how clever I aspire to be."