A £20,000 fine imposed on pro-Brexit supporter Darren Grimes by the UK’s elections regulator has been overturned by a judge at a court in London.

Grimes, who founded the youth Brexit group BeLeave when he was a student, said he was “delighted and relieved” to win the appeal. 

The Electoral Commission believes the £675,000 spent by BeLeave should have been declared by Vote Leave, the principal campaigner for a leave vote in the EU referendum, as it concluded the two groups had coordinated, within breach of the rules.

Earlier this week, Grimes’ lawyers accused the Electoral Commission of errors and irregularities in its decision to fine him for breaking referendum spending laws.

In a statement released on Twitter, Grimes said he was “delighted and relieved” the court has found him “innocent”.

“This case has taken a huge toll on myself and my family, and I’m thankful it’s now over. I will be eternally grateful to all those people who have supported me – your generosity and kind words of encouragement have kept me going.

“The Electoral Commission’s case was based on an incorrectly ticked box on an application form -something that it had been aware of for over two years and had not been raised in two previous investigations. Yet the Commission still saw fit to issue an excessive fine and to spend almost half a million in taxpayer cash pursuing me through the courts. This raises serious questions about its conduct both during and after the referendum.

“It’s vital that more young people are encouraged to get involved in politics and make their voices heard. I just hope that the punitive actions of the Electoral Commission don’t put my generation off from engaging in our democracy.”

An Electoral Commission spokesman said: “We are disappointed that the court has upheld Mr Grimes’ appeal. We will now review the full detail of the judgement before deciding on next steps, including any appeal.”