They hope to back up their bold claim that Warhol "had the greatest impact of any artist in the past 50 years"

The decorative qualities of the pop artist put him in a tradition dating back to the 18th century

The artist’s foundation reveals its intention to become one of the largest grant-making organisations in the country

While some fear the negative effects of the closure of the vetting board, others say its role was not essential

Few will mourn its demise

Poignant footage of Reverón's twilight years, Hockney playing the documentarian and Jeremy Deller in conversation with Anthony d'Offay on Warhol's transformative power

Joe Simon-Whelan spent three years trying to prove authenticity of a painting depicting the artist himself

A broad range of works reap favourable prices

Simon-Whelan says he lacks the financial resources to pursue his case

Sarah Morris, Mark Bradford, and Andy Warhol are this season's London highlights

Authentication board says famous museum director “falsified” their history

Gagosian among four called to court

The market has recalibrated, but major pieces spark highly charged bidding wars

A $1m reward is being offered

Collector says a signed work from the same series confirms his work is genuine

Owner cancels reward for his missing set, citing problems with his insurer

Twenty Factory regulars look back on the creative freedom that fuelled the New York enterprise, while three art schools are brought under the microscope

The large-scale “disaster painting” is the most expensive Andy Warhol ever to sell at auction

UK auctioneer says Pietro Psaier worked in The Factory and died in the 2004 tsunami; his body has never been found

Former Factory assistant claims he made the disputed work

The series will go on show at the Faurscho gallery in Beijing

Jason Beltrez claims it was a flea market find while Christie's is stuck in the middle

The New York organisation has disbursed more than $200m in cash grants and art donations since the artist's death in 1987

Movie producer Joe Simon-Whelan sues, believing his work is genuine

The Andy Warhol Foundation for the Visual Arts has awarded the museum $600,000

A source close to the Andy Warhol Authentication Board hints at a change of heart

Allegations circulate that curator Pontus Hultén created unauthorised replicas

Charges focus on former executive director of the New York Academy of Art

Each of the twelve motorists have been assigned a vehicle restored by Christie, their route incorporating a series of art fairs

The work is one of the “Death and Disaster” series which rarely come on the market