The US billionaire who declined to sell a rare Old Master painting to London’s National Gallery has hit back at critics who he says have “battered” him over his decision.

‘Portrait of a Young Man in a Red Cap’ (1530) by Pontormo, real name Jacopo Carrucci, was temporarily barred from export in December 2015 after it was purchased by Blackstone asset management group partner, J Tomilson Hill. The bar was enforced by the former Culture Minister, Ed Vaizey, to allow time for a UK buyer to match the asking price and save the painting for the British nation.

After a monumental campaign led by the National Gallery in which it successfully raised £30,618,987 to purchase the work, Hill rejected the Gallery’s offer. In reaching his decision, he cited the £8 million loss he would suffer due to the post-Brexit devaluation of the pound against the US dollar.

Accused of reneging on his agreement with the National Gallery, Hill staunchly defended his refusal to accept its offer. “There have been some false statements … I didn’t renege. I always had the right to say no”, he told the Guardian. Hill also dismissed the suggestion that he flouted export rules and denied reports that the painting’s original owner, the Earl of Caledon, sold it to him off the National Gallery’s wall.

Hill is correct that an applicant for an export license must confirm whether he is in principle willing to accept a matching offer, but is not bound to do so if an offer is made. However, this can, as in this case, lead to a huge amount of wasted effort in raising funds if an applicant rejects the offer. This has led to calls for reform to the current export system. In January this year, the Director of UK charity Art Fund, Stephen Deuchar, called for the rules to be strengthened to prevent an exodus of art and cultural treasures from the country as a result of “gentleman’s agreements”.

The ‘Young Man’ remains in storage in the UK.