On the bright yellow walls of Grayson Perry’s Summer Exhibition, among 1200 other works sits a painting by the famously anonymous street artist, Banksy. And yet, Banksy submitted a painting to the Summer Exhibition which was not selected by the judges, he revealed on Instagram this week. So what’s the story?

The Summer Exhibition, this year celebrating its 250th birthday, is an open submission exhibition – which means anyone can enter, and their work is judged anonymously by a panel of leading artists, co-ordinated this year by Grayson Perry RA. The panel also invite a range of established artists to exhibit work alongside the successful public entries, as well as work by Royal Academicians (the elected body of artists who run the Royal Academy), this year including David Hockney, Rose Wylie, Tracey Emin and many more.

We now know that among this year’s 20,000 public entries was a work by Banksy, submitted under the pseudonym “Bryan K Gasmaan” – an anagram of “Banksy anagram” – though the judges wouldn’t have seen the name under which it was submitted. This work wasn’t selected by the judges.

Later, when Grayson Perry came to select his “invited artists” to exhibit alongside the successful public entries, he approached Banksy with an invitation to exhibit a work. Accepting the invitation, Banksy chose to submit a different work from his rejected public submission, Vote to Love, which you can see hanging in Gallery III today. The work shows an altered “Leave” placard from the 2016 Brexit campaign.

Banksy isn’t the only well known artist to have been rejected by the judging panel, and Summer is renowned for the colourful stories that have emerged over its 250-year history. Masters including Édouard Manet, John Constable and Wyndham Lewis were all famously not to the tastes of the particular judging committees in their respective years.

As Grayson Perry puts it, “Everyone who submits work, you’re in the mix… it’s a democracy, you know, of a sort – a very arbitrary one: I’m in charge!”

250th Summer Exhibition and The Great Spectacle: 250 years of the Summer Exhibition are at the RA to 19 August.