Jeffrey Donaldson has been found guilty of 18 sexual offences against two victims who were children at the time of the abuse more than 30 years ago.

The former Democratic Unionist party (DUP) leader was remanded into immediate custody after a jury at Newry crown court on Monday convicted him of 18 offences including rape, indecent assault and gross indecency. The judge, Paul Ramsey, said a “lengthy” prison sentence was inevitable.

Standing in the dock with his hands clasped, Donaldson, 63, showed no visible emotion and stared straight ahead as he was found guilty of each charge.

The verdict completed a stunning fall for an establishment figure who had dominated unionism and played a key role at Westminster during post-Brexit negotiations over Northern Ireland’s position in the UK.

The jury found that Donaldson’s wife, Eleanor, had aided and abetted her husband’s offending. The judge deemed the 60-year-old unfit to stand trial on mental health grounds so she faced a trial of facts, which tests evidence but does not result in a criminal conviction.

In a four-week trial, Donaldson, 63, pleaded not guilty to one count of rape and other counts of gross indecency and indecent assault spanning a period from 1985 to 2008.

Prosecutors had urged the jury of five women and seven men to recall the “pain and hurt still so visible” on the two victims, referred to as complainants A and B. “The sexual abuse they suffered has consequences – consequences that cannot be ignored and brushed under the carpet any longer,” said Rosemary Walsh KC.

Complainant B told the trial she still lived with the memory of Donaldson’s assault: “What happened that night will live with me for ever.”

The verdict will shred what was left of the reputation of the former Lagan Valley MP, a polished media performer and towering political figure in Northern Ireland who helped to broker the Windsor framework.

His arrest in March 2024 shocked Westminster and Stormont. Donaldson stood down as an MP and resigned from the DUP, which scrubbed his name and image from its website and appointed Gavin Robinson as the party’s new leader.

A phalanx of cameras greeted Donaldson each day as he arrived at the court in Newry, 40 miles (65km) south of Belfast. Flanked in the dock by court employees, he appeared composed and took notes during proceedings and for two days in the witness box proclaimed his innocence.

Complainant B said she was raped when she was of primary school age and was of secondary school age when Donaldson lifted up her top and fondled her breasts. The jury heard that Donaldson’s wife witnessed part of the latter incident and walked away.

Complainant A said she was of primary school age when Donaldson began to be “physical” with her and put his hands up her top. She recalled waking up in the night on several occasions with a sexual feeling and having nightmares about “men doing horrible things to children”.

Once he kissed her and put his tongue in her mouth, and when she later complained, he laughed it off as a joke, the court heard. Donaldson also used a light to look at her genitals, she said.

The trial heard that in the 1990s the victim told a pastor about the abuse, after which Donaldson met and apologised to her at a Christian centre in County Antrim. Prosecutors also told the jury of a letter Donaldson wrote to Complainant A in 2020 in which he expressed regret for causing “hurt, pain and distress” and asked forgiveness for his “sinful nature”.

Donaldson said those apologies referenced other matters, not abuse, which he said never happened and was made up by the complainants.

Walsh said both victims kept memories “locked away inside” until reaching “turning points” in adulthood that prompted the “huge, huge” decision to report the offences to police in 2024. Neither woman had complete recollection and some memories were “fragmentary” but they were telling the truth, Walsh said. “This is what happened and they have made a decision to call it out.”

The prosecutor said Eleanor Donaldson knew of the risk her husband posed but instead of intervening she “facilitated” the abuse. The trial heard Jeffrey Donaldson had had a brief affair with a woman in 2008 and his wife, suspecting another affair, had a listening device planted in his car in 2020.

Donaldson’s barrister, Kieran Vaughan KC, said there was no medical or forensic evidence and urged the jury not to be “swept along” on a tide of emotion: “When all is said and done that is what it is about, their word against his word.”

He disputed the complainants’ accounts, saying some claims defied belief and were “farcical”. For the jury to convict, they “must be sure”, said Vaughan. “Nothing less will do. Suspicion is not good enough. You have to be sure.”

Until his arrest Donaldson had embodied unionist probity. Born into a Presbyterian family in the fishing village of Kilkeel, he married Eleanor in 1987 and served apprenticeships in the Ulster Unionist party before defecting to the DUP in 2003. He was knighted for political services in 2016 and became DUP leader in 2021.

Jim Allister, the leader of the Traditional Unionist Voice, called for Donaldson to be stripped of the knighthood.

The National Society for the Prevention of Cruelty to Children said the former DUP leader had betrayed his position of trust in the community. “The victims in this case, now adults, have shown immense courage in coming forward and giving evidence after decades of living with the impact of Jeffrey Donaldson’s abuse.”

• Information and support for anyone affected by rape or sexual abuse issues is available from the following organisations. In the UK, Rape Crisis offers support on 0808 500 2222 in England and Wales, 0808 801 0302 in Scotland, or 0800 0246 991 in Northern Ireland. In the US, Rainn offers support on 800-656-4673. In Australia, support is available at 1800Respect (1800 737 732). Other international helplines can be found at ibiblio.org/rcip/internl.html