Image copyright Getty Images Image caption Alun Cairns told BBC Wales he only became aware of Mr England's role in the trial's collapse when the story broke last week

A senior Welsh Conservative says it looks "very difficult" for Alun Cairns to lead the party's general election campaign in Wales after his former aide "sabotaged" a rape trial.

Ross England made claims about the victim's sexual history in an April 2018 trial which led to its collapse.

Welsh Secretary Mr Cairns denied knowing about this, but BBC Wales has seen an email sent to him in August 2018 mentioning the matter.

Mr Cairns has been asked to comment.

Meanwhile Tory Monmouth candidate David TC Davies has said Mr England should step down as a candidate for the 2021 Welsh Assembly election if he had been responsible for "bringing down" the trial.

Mr England said he had given an "honest answer" while giving evidence at the rape trial of his friend James Hackett.

With Prime Minister Boris Johnson set to launch the Conservatives' UK election campaign later on Wednesday, a senior Welsh Conservative said there was "increasing anger and alarm" among the party's general election candidates about Mr Cairns's knowledge of the collapsed rape trial.

The source added: "It looks very difficult to see how Alun Cairns can lead the campaign in Wales without fully explaining the circumstances surrounding this case."

Another source said: "Our three priorities in the national campaign outside of Brexit are law and order, NHS and schools. He is undermining one of those."

First Minister Mark Drakeford called for Mr Cairns's resignation and said it was "difficult to see how he can carry on".

He told BBC Radio Cymru that the Conservatives were "out of touch with people and Mr Cairns's predicament is an illustration of that".

On the matter of Mr England, Mr Davies told BBC Radio Wales he did not know the details of the case, but said: "It does need to be thoroughly investigated, absolutely.

"If he [Ross England] is responsible for bringing down a rape trial then clearly he wouldn't be a fit person to be a candidate."

Asked if Mr England should step down if that was true, Mr Davies said: "Well, if that's true, of course, yes."

Image caption Mr England gave a speech at the Welsh Conservative conference in 2016

At the trial, Mr England told the court he had had a casual sexual relationship with the complainant - which she denied - despite the judge in the case making it clear that evidence of the sexual history of the victim was inadmissible.

The judge, Stephen John Hopkins QC, said to him: "You have managed single-handed, and I have no doubt it was deliberate on your part, to sabotage this trial… get out of my court."

James Hackett was subsequently convicted of rape at a retrial.

In December 2018, Mr England, who used to work for Mr Cairns in the Vale of Glamorgan, was selected as the Conservative candidate for the seat at the 2021 Welsh Assembly elections.

Last week, he was suspended as a candidate and as an employee after details of the court case emerged as the party said a "full investigation will be conducted".

Following the suspension, Welsh Conservative party chairman Lord Davies of Gower said the party only became aware of the "full extent of the proceedings" when Hackett's appeal process ended in October.

Lord Davies said he could "categorically state" he and Alun Cairns were "completely unaware of the details of the collapse of this trial until they became public this week".

The Welsh secretary told BBC Wales in a statement when the story broke that he only became aware of the collapse of the trial "some considerable time afterwards and had no knowledge of the role of Ross England".

But BBC Wales has seen an email sent on 2 August 2018 to Mr Cairns by Geraint Evans, his special adviser, which said: "I have spoken to Ross and he is confident no action will be taken by the court."

Image caption Mr England was selected to stand for the Welsh Conservatives for the 2021 assembly election

A spokeswoman for the Welsh Conservatives said: "There is no new information from this leaked document confirming an informal conversation which took place a considerable time after the trial collapsed and is consistent with statements made.

"The full details of this case are still not known and we have taken action in writing to the court. All forthcoming information will be taken into account as the party conducts a thorough investigation," the statement read.

The rape victim has called for Mr Cairns to resign.

She said: "If he'd come out and condemned Ross [England] in the first instance, he wouldn't be in this position.

"I would like an apology from the party and Alun Cairns for selecting him in the first place. I can't believe that not one senior Welsh Conservative has said that what he did was wrong."

'Highest integrity'

But speaking on the BBC's Newsnight programme on Tuesday night, the former Conservative minister and chief of staff to Theresa May, Lord Barwell, said it was a "highly sensitive issue and the Welsh Conservatives have launched an investigation".

He added: "I don't know the detail of that and I don't want to comment further other than to say to you that I know Alun Cairns well and he's someone I would regard of being of the highest integrity.

"So, I'm surprised to find him caught up in this and I hope that investigation would demonstrate that he hasn't done anything wrong."

Plaid Cymru's parliamentary leader Liz Saville Roberts has written a letter to Boris Johnson calling on him to remove Mr Cairns from his cabinet and as a Conservative candidate.

In the letter, the Dwyfor Meirionydd MP said: "At best Mr Cairns has displayed gross incompetence in judgement showing himself completely unfit for public office."

She said that if the prime minister would not listen to her, she urged him to "please listen" to the victim.

"Show some leadership on this deeply distressing issue," she added.

BBC Wales has asked the prime minister for a response to Ms Saville Roberts's letter.