Banksy may be forced to reveal his identity if he is serious about trademarking his work.

The anonymous graffiti artist, who was first noticed in the early 1990s for spray painting walls and trains around his home town of Bristol, has reached worldwide acclaim, all the while keeping his identity a secret.

But the feasibility of his anonymity has recently been cast in the spotlight after a ruling from the European Union Intellectual Property Office (EUIPO) revoked the trademark previously afforded him for his artwork The Flower Thrower.

In 2014 Banksy applied for an EU trademark for the graffiti mural that he had painted on a wall in Jerusalem in 2005.

The artwork, which is also sometimes referred to as Love is in the Air, depicts a protestor throwing a bunch of flowers and has been reproduced around the globe. But it was the use of the artwork on its greeting cards by UK card company Full Colour Black that prompted Banksy to successfully apply for a trademark.

According to the UK’s Independent, the 2014 ruling was challenged by the card company, which argued that Banksy was not entitled to the trademark as he did not intend on using the image for trade or branding purposes.

In response to the challenge, Banksy opened an online shop in October last year and started selling a range of merchandise, including reproductions of the image in question, to fulfil these trademark requirements.

But last month the EUIPO ruled in favour of Full Colour Black and declared the previous trademark “invalid in its entirety”, saying Banksy had filed the trademark in bad faith.

It quoted Banksy’s long-held view that “copyright is for losers” and his insistence on remaining anonymous as two of the deciding factors in the ruling.

In an article on BristolLive, the examiners were quoted as saying, “It must be pointed out that another factor worthy of consideration is that he cannot be identified as the unquestionable owner of such works as his identity is hidden. It further cannot be established without question that the artist holds any copyrights to a graffiti.”

There has since been no move on the part of the artist to reveal his identity in an attempt to overturn the ruling.

It also seems to have had no bearing on the impending sale of his painting, Show Me the Monet, which is expected to sell for a staggering price of between £3-million  and £5-million at a Sotheby’s auction on 21 October.