Major London sites were shut down as the group moved to enter administration through the courts following missed payments to staff and subcontractors.

Group businesses affected include Ardmore Major Projects, Ardmore Hotels & Commercial, Ardmore Regeneration, Ardmore Fitout and Landmark Facades.

More than 500 staff are expected to be impacted.

The collapse of the £350m turnover group leaves a string of high-profile London projects in limbo, with clients now scrambling to line up replacement contractors to complete schemes.

At the time of its failure, Ardmore was delivering around 10 major projects across the capital, including luxury hotel developments in Mayfair and Kensington, two residential tower schemes and a major life sciences laboratory campus at King’s Cross.

The administration marks the latest chapter in the group’s long-running battle to contain liabilities arising from historic residential developments requiring extensive fire safety remediation following post-Grenfell regulatory changes.

Nearly a year ago, Ardmore Construction, the original contracting arm responsible for delivering many of the affected schemes, was placed into administration in an attempt to ringfence the wider group from future claims.

However, a landmark legal challenge brought by house builder Crest Nicholson changed the landscape.

The High Court ruled that Building Liability Orders introduced under the Building Safety Act 2022 could be used to extend liability for building defects beyond the original contractor to parent companies and associated businesses within the same corporate group.

The judgment, which Ardmore still intends to appeal, potentially opened the door for other developers and building owners to pursue claims against companies across the wider Ardmore group, significantly increasing the firm’s exposure.

Several major house builders, including Barratt, Taylor Wimpey and Bellway are pursuing major claims against the group.

Industry sources said growing uncertainty over the scale of potential liabilities had increasingly weighed on the group’s ability to win fresh contracts, with clients and funders becoming more cautious despite Ardmore’s substantial live workload.

Administrators are expected to assess options for the affected businesses while clients seek alternative contractors to complete unfinished projects across London.

Meanwhile, the wider Ardmore Group, which includes its property business, has not entered into administration but has applied to enter into a moratorium process, which will allow it to continue trading while its position is reviewed.

This step is intended to allow Ardmore to continue preparing its appeal against the High Court BLO judgment in the Crest case.

Earlier this week, Ardmore was granted permission to appeal to the Court of Appeal, with the Court also granting expedition given the importance of the issues raised.

Ardmore believes the appeal raises issues of wider public importance for the construction industry, including the circumstances in which a Building Liability Order may be made and the extent to which liabilities may be imposed on group companies in respect of historic projects.

A spokesperson for Ardmore said: “This is a deeply disappointing outcome for the construction group, its employees and its stakeholders.

“Our focus is now on preserving value in the wider Group, protecting the continuing businesses where possible, and pursuing the appeal against a judgment which we believe raises important questions for the wider industry.”