A UK cabinet minister who denied knowing about a Welsh assembly candidate’s role in “sabotaging” a rape trial was emailed about it last year.
Ross England made claims about the victim’s sexual history in an April 2018 trial which led to its collapse.
BBC Wales has seen the email sent to Welsh Secretary Alun Cairns in August 2018 about his former aide’s role. Mr England was picked as the Tory assembly election candidate in December 2018.
Mr Cairns has been asked to comment.
The email on 2 August 2018 was sent to Mr Cairns by Geraint Evans, his special adviser. It was also copied to Richard Minshull - the director of the Welsh Conservatives - and another member of staff.
It said: “I have spoken to Ross and he is confident no action will be taken by the court.”
Mr England, who was selected as the candidate for Vale of Glamorgan, said he had given an “honest answer” in the rape trial.
At the time of his selection, Mr Cairns endorsed Mr England as a “friend and colleague” with whom “it will be a pleasure to campaign”.
A Welsh Conservatives source told the BBC: “I can’t really see how he can possibly carry on - the toxic nature of these revelations could bring down the whole Conservative campaign in Wales.
“If he did have any decency he’d put the party and country first and resign.”
Mr England was suspended as a candidate and employee last week and the party said a “full investigation will be conducted”.
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.”
At the trial of James Hackett - a friend of Mr England’s - he told the court he 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 Mr England: “Why did you say that? Are you completely stupid?
“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.”
Hackett was subsequently convicted of rape at a retrial.
Christina Rees, Labour’s shadow secretary of state for Wales, said: “There are no two ways about this - Alun Cairns has been caught brazenly lying about how much he knew of Ross England’s appalling behaviour at a rape trial.”
She said the decision to select Mr England as a candidate was “an error of judgement - the cover up is unforgivable” and called on Mr Cairns to resign.
Echoing the call, Plaid Cymru MP Liz Saville Roberts said: “At worst, Mr Cairns is complicit in the attempted cover up of his former staff member’s actions which collapsed a rape trial.
“At best, he has displayed gross incompetence in judgement, dishonesty and a lack of leadership.”
In the first of two statements issued on Thursday, Welsh 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.
He said: “We were fully aware that Ross England was involved as a witness in a sensitive case. We are also aware of the responsibility we have as employers.
“Since the end of the Appeal Court case, we have now been made aware of the full extent of the proceedings.”
In a second statement, he said he could “categorically state” he and Mr Cairns were “completely unaware of the details of the collapse of this trial until they became public this week”.
Mr England used to work for Mr Cairns in the Vale of Glamorgan and was selected as the party’s candidate to fight for the constituency seat at the 2021 Welsh assembly elections.
Mr Cairns told BBC Wales he only became aware of Mr England’s role in the trial’s collapse when the story broke last week.
In a statement, he said he only became aware of the collapse of the trial “some considerable time afterwards and had no knowledge of the role of Ross England”.
Mr England said he acted honestly during the collapsed trial and was not aware that any evidence had been ruled inadmissible.
The victim said Mr England’s Conservative selection “shows how little respect they have for me”.
She added: “It is completely shocking to me that Ross England would stand up in court and say these things given that they are untrue.
“He was asked if we worked together, and the answer to that is yes.
“Nobody asked him if we were in a sexual relationship or not. For him to just blurt that out proves to me that it was a formulated plan that he and whoever else conjured to try and derail the trial.
“I think it was an absolutely deliberate attempt to sabotage the trial.”
In a statement, Mr England said: “I gave an honest answer, honouring the oath I took to tell the truth, the whole truth and nothing but the truth.
“I complied fully with the conditions of the court before and after the trial.”
One Conservative Party source told BBC Wales they called the party’s Cardiff headquarters on the day the trial collapsed to inform management Mr England’s actions led to that happening.
Judge Hopkins went on to say he would be writing to Mr England’s political allies in the hope they would take “appropriate action”.
Lord Davies has said “at no time” had any party officials received any correspondence in relation to the matter.
Mr Evans and Lord Davies have also been asked to comment.