Christian Horner’s Formula One career remains in the balance after he was questioned by a lawyer for eight hours on Friday.

The embattled Red Bull team principal, 50, was answering an accusation of “inappropriate behaviour” by a female colleague – a claim he categorically denies.

Horner’s interview took place at a secret London location.

It had originally been diaried for Red Bull Racing’s Milton Keynes headquarters.

But such has been the level of interest in the allegations against Horner, which emerged publicly on Monday, a change in venue was sourced.

Neither Red Bull Racing, who last year helped Max Verstappen win his third world championship, nor its parent company Red Bull GmBH – who are carrying out the investigation – commented about the details of the hearing which the PA news agency understands started at 10am and ran until the early evening.

Red Bull are set to unveil their car for the new season next Thursday, and there had been a strong desire for Horner’s future to be resolved before then.

But sources have indicated that is now looking highly doubtful, with the likelihood of Horner facing subsequent rounds of questioning as he bids to prove his innocence.

Indeed, it is thought the investigation may not be wrapped up before pre-season testing gets under way on February 21, and could rumble on until the opening round in Bahrain on March 2, and possibly beyond.

Horner has been Red Bull team principal since they entered F1 19 years ago and is the longest-serving boss on the grid.

During that period he has overseen seven drivers’ world championships and six constructors’ titles.

Red Bull have dominated the sport in recent seasons and last year won 21 of the 22 races, with Verstappen setting a new record for 10 consecutive victories.

For now, Horner remains in his role, and it is still anticipated that he will attend the team’s season launch in Milton Keynes next week.

A spokesperson for Red Bull GmBH said earlier this week: “After being made aware of certain recent allegations, the company launched an independent investigation.”

It added that “the company takes these matters extremely seriously.”

In response to the allegations, Horner said: “I completely deny these claims.”