The victim said he wasn’t “taken very seriously” when he made the allegation to the Conservative Party press office days before Khan, 48, was elected in the December 2019 general election.
He made a complaint to police days after Khan helped Prime Minister Boris Johnson win a large Commons majority by taking Wakefield in the so-called “red wall” that had formed Labour’s heartlands in the Midlands and northern England.
Southwark Crown Court heard how Khan forced the teenager to drink gin and tonic, dragged him upstairs and asked him to watch pornography before the attack at a house in Staffordshire in January 2008.
The victim, now 29, told a jury he was left feeling “scared, vulnerable, numb, shocked and surprised” after Khan touched his feet and legs, coming within “a hair’s breadth” of his privates.
He ran to his parents and a police report was made at the time, but no further action was taken because the youngster did not want to make a formal complaint.
But he told jurors “it all came flooding back” when he learned Khan was standing in the December 2019 general election.
The Tory hopeful was literally parachuted into the constituency in a skydiving stunt after he was selected to replace Antony Calvert weeks before the election.
Days ahead of the poll, the victim said he contacted the Conservative Party press office, to tell them what Khan had done to him, but added: “I wasn’t taken very seriously.”
Khan, who was sent a questionnaire by Staffordshire Police rather than being interviewed under caution at a station because of “Covid protocols in place at the time”, denied sexual assault.
The MP, who is gay and a Muslim, claims he only touched the Catholic teenager’s elbow when he “became extremely upset” after a conversation about his confused sexuality.
Khan, then 34, said he was trying to be “kind” and “helpful”, but the teenager became upset and “bolted” when the topic of pornography was raised.
But Khan, who has been suspended by the Conservative Party, was found guilty by a jury at Southwark Crown Court on Monday by a jury after around five hours of deliberations.
The judge, Mr Justice Baker, said he will sentence Khan at a date to be fixed.
He will be thrown out of the House of Commons if he is handed a prison sentence of more than a year, or otherwise could be subject to a petition to oust him in the recall process.
The judge released Khan on bail, telling him: “You have been convicted by a jury of this offence of sexual assault and you will have to be sentenced in due course.
“I make it clear that all sentencing options, including immediate custody, are being considered by the court.”
Tory MPs Crispin Blunt and Sir Peter Bottomley, the father of the House of Commons, attended court on Monday, while a third, Adam Holloway, earlier provided a character statement used as part of Khan’s defence case.
The victim said he “vividly” remembered the gin bottle Khan took to the party, the smell of the spirit in the glass tumbler, and the fizz of the bubbles as he was forced by Khan to drink the cocktail.
He said Khan also watched him do pull-ups, asked him to watch pornography and told him he was “good looking” in a “love whisper” in his ear, which was “disgusting and really slimy”.
The victim said he pretended to be asleep before Khan went to touch his feet.
“He was drunk because I could hear his heavy breathing,” he said.
The complainant said the “slow caressing” continued as Khan works his way “up my leg”, despite him telling the MP to stop.
He said he “froze”, adding: “I freaked out and ran as fast as I could.”
The boy’s brother, who was 18 at the time, told jurors he was also the victim of an “assault” when Khan asked if he was wearing his kilt like a “true Scotsman” – referring to the tradition of wearing the garment without underwear – before lifting it up with both hands.
During legal argument, prosecutor Sean Larkin QC said it was a “mere technicality” that Khan had not been charged with a second sexual assault of a man at a guesthouse in Pakistan, where the MP was working on a Foreign Office-funded project.
The alleged victim, then in his mid-20s, said Khan performed a sex act on him in his sleep after offering him a sleeping pill as they shared a room following an evening of drinking whiskey and smoking marijuana.
The man told jurors he reported the November 2010 incident to the British High Commission and the Foreign Office but did not want to go to police in Pakistan because of Khan’s “powerful connections” in the military and government.
He came forward as a witness after hearing Khan had been charged with sexual assault following the MP’s failed bid to gag the press from reporting his name.
It is understood a charge could not be brought because the alleged assault took place outside the jurisdiction before a change in the UK law.
Khan claimed the sexual activity was consensual.