A Banksy painting showing a young boy playing with a toy nurse as a superhero rather than Batman or Spider-Man sold for more than $20 million on Tuesday, setting an auction record for the elusive British street artist.

“Game Changer”, which was unveiled last May at University Hospital Southampton, paid tribute to the frontline workers of Britain’s National Health Service (NHS) in their fight against the COVID-19 pandemic.

The black-and-white artwork shows a young boy lifting a nurse, her arm stretched and wearing a cape, while traditional superheroes Batman and Spider-Man lie in a bin.

In a Christie’s auction streamed live, the painting sold for a hammer price of 14.4 million pounds ($19.85 million). Added fees gave it a final price of 16.758 million pounds ($23.10 million), a world auction record for Banksy, according to Christie’s.

The painting had carried an estimate of 2.5-3.5 million pounds. Christie said proceeds would go towards “support(ing) the wellbeing of University Hospital Southampton staff and patients”.

The sale took place as Britons across the country on Tuesday marked one year since Prime Minister Boris Johnson ordered the nation into its first lockdown.

A minute’s silence was observed to remember the more than 126,000 people who have lost their lives since the virus.