Campaigners who lost the latest legal battle against possible expansion at Stansted Airport last night said they are undecided about whether to take the judgement to appeal.

The Stop Stansted Expansion group (SSE) yesterday had their application for a judicial review turned down after a High Court judge rejected their accusation that the key criteria being applied to decide on potential options for new runway sites in England were “infected by apparent bias”.

The group had asked Mrs Justice Patterson, sitting in London, to order the Government-appointed Airports Commission, which was set up last year to address the issue of aviation expansion in the UK, to delay the publication of any options short-list until the criteria have been looked at again and consulted on.

SSE said there was apparent bias because of the conduct of Geoff Muirhead, a recently resigned member of the Commission.

Aviation expert Mr Muirhead is a former chief executive of Manchester Airports Group (MAG), the owner of Stansted since February. In September, he stepped down as one of the five commissioners appointed by the Commission after SSE warned Transport Secretary Patrick McLoughlin they would take legal action if he stayed.

SSE said he retired as MAG’s chief executive after 22 years with the group but was then immediately reappointed as “a highly paid ambassador to MAG, a role he continued to fulfil even after he was appointed to the Airports Commission”.

The court heard that MAG submitted proposals to the commission for a two-runway option at Stansted, and a four-runway hub airport option which would make Stansted the largest airport in the world.

But although the judge ruled that both Mr Muirhead and the commission might have acted in a way that was not “the most wise”, she said a “fair-minded and informed observer” would not have been satisfied there was “a real possibility of bias”.

In a statement after the ruling, SSE, who were ordered to pay legal costs of up to £10,000, said: “Although SSE has achieved its principal objective in pursuing this legal challenge, namely the removal of Mr Muirhead from the commission, SSE still has some concerns about the integrity of the process going forward.

“Some of SSE’s concerns were addressed in the course of the legal proceedings as a result of confidential information disclosed by the commission in witness statements and exhibits, including the minutes of internal meetings.

“Despite its public commitment to be open and transparent, the Airports Commission considers that it is not subject to the Freedom of Information Act. Therefore, much of the information released to SSE as a result of its legal proceedings could not otherwise have been obtained.

“Because there is so much at stake, and because the position is still not entirely satisfactory, SSE needs time to give proper consideration to the judge’s 60-page ruling and to discuss it in detail with its legal advisers before deciding whether there are aspects of the judgment that need to be taken to the Court of Appeal.