A British woman who accused a senior United Arab Emirates royal of sexually assaulting her has issued a formal claim for damages.

Caitlin McNamara is claiming damages for multiple sexual assaults and false imprisonment she allegedly suffered at the hands of Sheikh Nahyan bin Mubarak Al Nahyan on 14 February 2020 at a private residence in Abu Dhabi.

Her lawyers said today that she was compelled to take the step after the refusal of the British authorities to prosecute Nahyan, the UAE’s minister for tolerance and coexistence.

In effect, the letter gives the sheikh an opportunity to hold his hands up and potentially offer an out-of-court settlement. The likelihood of that remains an open question.

Civil proceedings will be brought if necessary in the high court in London, according to the law firm Carter-Ruck, which has been engaged by McNamara.

McNamara, who was the curator of the first Hay festival in Abu Dhabi in February 2020, went public with her accusations last year.

She alleges that the sheikh attacked her shortly before the festival, which his department had funded.

She had believed she would be attending a business meeting with the royal, who denies the allegations. His London lawyer said: “Our client is surprised and saddened by this allegation, which arrives eight months after the alleged incident and via a national newspaper. The account is denied.”

In Britain, the Crown Prosecution Service declined to prosecute Nahyan, arguing that there was not enough evidence that he was acting in his official duties during the alleged attack.

In an article she wrote for the Guardian last month, McNamara said she had always known how hard it would be to get criminal justice, because of the sheikh’s status.

“When the civil route was first suggested, I was adamant I did not want to sue,” she added. “I felt sick at the thought of a financial price being put on my pain. I was also acutely aware of Nahyan’s wealth, and how this might be perceived. But after a long year of learning from campaigners, legal experts and other survivors, I think differently.”

McNamara – who sought a judicial review of the CPS decision and was told in December that it was being confirmed – said it was hard not to feel like collateral damage against the backdrop of Britain’s relationship with the UAE.

Also in December, Prince Charles and Boris Johnson had hosted three other members of the Al Nahyan family, including Crown Prince Sheikh Mohammed, sponsor of Hay festival Abu Dhabi. A statement released by Downing Street after that event said that Johnson was looking forward to the Dubai Expo. Nahyan will be commissioner-general of the event, which begin in October.