Former Manchester Airports Group chief executive Geoff Muirhead is standing down from the government’s Airports Commission following the threat of legal action from a protest group.

He is to leave the commission by mutual consent, the Department for Transport confirmed.

The Stop Stansted Expansion group claimed a conflict of interest as Muirhead retired from MAG in 2010 but continued to act as an advisor to the company, which now owns Stansted, until January – several months after he joined the Aviation Commission.

It threatened to apply to the High Court for a judicial review of the process if Muirhead refused to resign.

A statement from the Commission said: “The members of the Airports Commission would like to thank Geoff Muirhead for his valuable and insightful contributions to their work programme.

“Throughout his time with the Commission, he has consistently demonstrated his impartiality.

“However, while they regret that this decision has been necessary, they accept that in the changed circumstances following Manchester Airports Group’s submission of its proposals for expanding Stansted airport, it has become appropriate for Geoff to stand down to safeguard against any perception that the integrity of the process may be compromised.”

A DfT spokesman said: “Mr Muirhead was appointed to the Airports Commission in October 2012, at which point Manchester Airports Group did not own Stansted airport.

“MAG has since purchased Stansted and following its submission to the Airports Commission concerning options for the expansion of Stansted airport, questions have been raised about the appearance of a potential conflict of interest.

“Although there is no evidence whatsoever of bias towards the MAG submission concerning Stansted, we have agreed that the prudent course is for him not to continue as a commissioner to avoid any perception of a potential conflict of interest.

“We are quite clear that there is no implication against Mr Muirhead’s integrity, which is emphasised by the importance he has placed on maintaining public confidence in the work of the Airports Commission.”