A senior Number 10 source has hit out at “disgusting and untrue” reports of the alleged incident which have emerged in recent days. The source said Northern Ireland Secretary Conor Burns, who raised his concerns with colleagues after the pair broke out in 2018 before their relationship went public, “is adamant there was nothing physical going on”. They were not “in physical contact” with Burns, said the No 10 source, who said they had discussed the matter at length with him. Asked if Mr Johnson had been questioned about the matter, the source said: “No, it’s not why he was elected prime minister. It’s neither here nor there.” The Downing Street source said Mr Johnson’s private conduct as foreign secretary in his official parliamentary office was a legitimate matter of public interest, he said: “Connor said that is not true. They’re crazy old questions about a non-event many years ago before Boris got to Downing Street.” The Independent revealed on Friday that Burns was the mystery MP who walked in on Johnson and Miss Symonds. Burns “strengthened” the couple’s relationship with Foreign Office officials after finding them “drinking a glass of wine together” alone because he had a “sixth sense” that their relationship was “worthy of attention”, Downing Street said on Friday . A second source said Mr Burns, one of Johnson’s staunchest supporters, was “severely shaken” after bumping into Johnson and Miss Simmonds unannounced. At the time, he was Mr Johnson’s parliamentary private secretary – “the Boris who carries the bags” as he cheekily called himself – with free access to him. “He [Burns] I wanted to know what to do about it,” the source said. “His only concern was to protect Boris. He is devoted to him.” It has previously been reported that Mr Burns raised the issue with his colleague, Foreign Office aide Ben Gascoigne, who is now No 10 deputy chief of staff. Alerted to concerns that Mr Johnson was having an extramarital affair with Miss Symonds, Mr Gascoigne and other aides blocked Mr Johnson’s bid to appoint Miss Symonds as head of the £100,000-a-year Foreign Office. They also discussed fears that it could expose Foreign Secretary Mr Johnson to the risk of blackmail if the information fell into the hands of Britain’s enemies. A source said: “After Connor saw them together in his office, Boris’ staff knew it could be dangerous if the wrong people found out. They decided that his private life was his business, but prevented him from doing so [Carrie] his chief of staff because he would have increased his exposure.’ Johnson and Miss Symonds’ relationship went public several months later in 2018 after his split from his second wife, Marina, was announced. At the time of the incident witnessed by Mr Burns, Miss Simmonds was the Tory party’s head of communications. She left that position in the summer of 2018 following allegations that she had misused her expenses. The claim that Mr Johnson and Miss Symonds were in a “compromising situation” by an unnamed Tory MP was first made in a biography of Carrie Johnson by Tory Lord Ashcroft earlier this year. When the story resurfaced in The Times two weeks ago, it led to a row when the paper withdrew the story from later editions after No 10 intervened. On Friday, Downing Street confirmed to The Independent that an incident had occurred and that the mystery MP was 49-year-old Burns. The source said: “Connor did walk in on them. He saw two people sitting and drinking a glass of wine [one] she may have figured out where the relationship was headed. It didn’t interrupt anything. It was a case of “why are they having a drink?” and “let’s talk to Ben [Gascoigne].” “For this [Conor] he thought it was something to point out. It was about a sixth sense that this was a sensation to watch. The door was not locked. He didn’t go in. He walked in where they had a meeting earlier and were still chatting.’ At the height of the Partygate scandal, Mr Burns led the defense of Mr Johnson for attending a No 10 birthday party in his honour, which led to him being fined for breaching Covid containment laws. The MP downplayed the matter saying that the prime minister was “ambushed with a cake”. Burns was appointed trade secretary when Johnson succeeded Theresa May as Tory leader in July 2019. He stood down in 2020 and was suspended as an MP for a week after a parliamentary inquiry found he had made “veiled threats” to use the privilege to “advance the interests of his family” in a financial dispute involving his father. Mr Johnson appointed him Northern Ireland Secretary last September. Messrs Burns, Johnson, Johnson and Gascoigne declined to comment.