Opponents of Stansted Airport’s expansion have demanded a key advisor to the Davies Commission on airport capacity be removed.

The Stop Stansted Expansion campaign has threatened legal action to have former Manchester Airports Group (MAG) chief executive Geoff Muirhead removed from the commission’s panel on the grounds of conflict of interest.

Muirhead is one of five advisers appointed by commission chairman Sir Howard Davies (pictured).

Manchester Airports Group, the new owner of Stansted, has submitted plans to the commission outlining the case for a new runway at Stansted and for transforming the airport into a four-runway hub to replace Heathrow.

Muirhead spent 24 years running Manchester Airport until he retired in 2010 and remained employed as an “ambassador” until January this year when MAG took over Stansted.

The Sunday Times reported that Stop Stansted Expansion chairman Peter Sanders has written to the Department for Transport and to Davies questioning Muirhead’s role.

Davies had responded each time arguing there was “no impropriety” in the appointment.

The Davies Commission was set up by the government last year to examine the options for hub airport expansion in the southeast.

It is due to produce an interim report, including a shortlist of options, this year and a full report in 2015 after the next general election.