A woman who fled rape and torture in the Democratic Republic of the Congo 18 years ago and was denied British citizenship because she entered the UK illegally has won her case after a government U-turn.

It is thought to be the first victory under a new policy whereby citizenship applications from people such as refugees who enter the UK illegally will normally be refused. She successfully challenged the refusal in a high court case.

Ministers’ reasoning is that because refugees arrived here illegally they do not meet the “good character” requirements for British citizenship. The Refugee Council estimates that at least 71,000 refugees will be adversely affected by the policy announced in February.

The 48-year-old woman, who cannot be named, was jailed, raped and tortured in her home country because of her and her husband’s political opposition to the government at the time. He was later killed. She managed to escape with the help of an agent who travelled with her and provided her with a false passport to get out of the DRC. They flew to the Kenyan capital, Nairobi, and from there took a connecting flight to the UK. On arrival in the UK she claimed asylum and was granted it because her story of persecution was found to be credible.

She has three British children, has no criminal record and contributes to her community by volunteering at her local church.

She applied on 13 February this year after she had paid the British citizenship application fee of about £1,600. Her application was rejected, with Home Office citing the new rules relating to good character and illegal entry in the refusal letter.

In the letter, officials said applications would “normally be refused regardless of the time that has passed since the illegal entry took place. You have not provided any information that would persuade us to grant your application on an exceptional basis. The application fee for British citizenship is not refundable but £130 will be refunded because you are not required to attend a British citizenship ceremony.’

The woman’s lawyers challenged the refusal, arguing that she was of good character and that her illegal entry 18 years ago should be disregarded. They added that the Home Office’s decision was incompatible with international law, which provided a defence for refugees who had to travel in ways that would normally be illegal, such as by using false passports.

On 8 December, the woman received an invitation from the Home Office to attend a British citizenship ceremony.

“I went through a lot in my country and I was astonished and distressed when Home Office refused my British citizenship application. Now that the Home Office has changed its decision I’m very happy. I feel liberated and free,” she said.

Jed Pennington, of the law firm Wilsons Solicitors, who represented the woman, said: “Eighteen years ago, our client fled unimaginable horrors in her home country. An immigration judge accepted she was telling the truth about what had happened, and she was recognised as a refugee. Twelve years ago, she was granted indefinite leave to remain.

“She has rebuilt her life here, she is part of the community she lives in, her children are British. She has no criminal record. It is very difficult to understand a decision that she is not a person of good character now based on a breach of immigration law eighteen years ago, especially when the circumstances of this are considered.”

A Home Office spokesperson said: “We do not routinely comment on individual cases, but each citizenship application is assessed on its own merits based on the evidence submitted.”