The era of anonymity could be over for secretive street artist Banksy after police were called in about his latest work.

The mural, showing a judge using a gavel to beat a protester on the wall of London's Royal Courts of Justice, appeared yesterday and was immediately covered up by staff ahead of its removal from the listed building.

A Scotland Yard spokesman told HENI News: "On Monday, 8 September officers received a report of criminal damage to the side of the Royal Courts of Justice. Enquiries continue.”

If charges are brought and the artist ends up in court he will be required by law to reveal his real name and failure to do so would likely see him jailed for contempt of court.

Matthew Christopher Pietras, who built his reputation as a generous patron of the arts with other people's money, died of a drug overdose according to New York City's Office of Chief Medical Examiner.

The 40-year-old was found dead on May 30 - a day after the city's Met Opera was told the $10 million he had just donated was not his to give.

Yesterday it was confirmed by the authorities he had died from acute intoxication from a series of pharmaceutical drugs.

Pietras worked as an assistant to Gregory Soros, a son of billionaire investor George Soros, and also Courtney Sale Ross, the widow of the Time Warner chief Steven J. Ross and the families are working together to discover whether their money was used to fund his cultural largesse.

The opera house promptly returned the money while another of his beneficiaries, The Frick Collection, said it did not "believe that any of the contributions were made with misappropriated funds".

It is not clear how much Pietras gave the museum though the New York Times reported it was somewhere between $1 million and $4,999,999.

The gentleman's agreement that the National Gallery's collection ends at 1900 leaving Modern and Contemporary works to Tate has been blown out of the water to the tune of $508.9 million.

That's how much the National Gallery has attracted in funding for a new wing with the vast majority of it coming from the Julia Rausing Trust and the charitable foundation of Michael Moritz and his wife, Harriet Heyman, which both committed $203 million - the largest publicly reported single cash donations to a museum or gallery anywhere in the world.

Crucially for the National Gallery, it got the Tate on board before announcing the land grab which is diplomatically described as a move to "extend its historic collection" in an "exciting new collaboration" with its rival across London.

Trustees from both museums have already met to plan the joint venture and Tate Director Maria Balshaw welcomed the move which she says will see both institutions "working closely" on loans and "curatorial and conservational expertise".

The expanded Crystal Bridges Museum of American Art will open next June with 18 new works on show donated by its billionaire chairperson Olivia Walton and her husband Tom.

The works are all by women artists including Yayoi Kusama, Alice Neel and Njideka Akunyili Crosby and will be joined in the renovated museum by 200 pieces donated by collectors Candace and Michael Humphreys.

Visitors to the grand re-opening on June 6 and 7 will be the first to see the results of the expansion project that is increasing the size of the museum in Bentonville, Arkansas, by 50%.

Around 14 million visitors have walked through its doors since it was opened in 2011 by philanthropist Alice Walton whose wealth comes from the family ownership of the Walmart shopping chain.

1 - Billionaire collector John Pritzker has given a huge gift of Dada and Surrealist work to New York’s Metropolitan Museum of Art. The 188 works include pieces by artists including Man Ray, Marcel Duchamp and Kurt Schwitters.

2 - Another day, another new museum project for in-demand architect Lina Ghotmeh. The 45-year-old, who was recently appointed to renovate the British Museum in London, will lead the design of the Jadids’ Legacy Museum in Bukhara, Uzbekistan, which will focus on the history of Jadidism - a reform movement that spread across Central Asia in the 19th and 20th centuries.

3 - Berlin Art Week launches tomorrow with work by Mark Leckey, Charmaine Poh and Elizabeth Jaeger on show. The event, which runs to Sunday, includes the 12th edition of Positions art fair at Berlin-Tempelhof Airport and guided tours through the private homes of some of the city's collectors.