The firms, Heritage Building & Conservation and Heritage Building & Conservation (North),  were launched two years ago taking on skilled staff following the collapse of York-based conservation specialist William Anelay.

William Anelay had traded since 1747 but collapsed after its owners failed to rescue the business by securing a deal with creditors.

This risked seeing valuable restoration skills lost to the industry for good until many were taken on by Heritage Building & Conservation.

Gordon Verhoef, the man behind the London-based national stone and conservation contractor Szerelmey, bought the firms which remained separate to Szerelmey.

But now two have fallen into administration.

A separate company, Heritage Building & Conservation (South), is not in administration and trades solvently.

One former employee told the Enquirer: “We were told that everything was fine only months ago and suddenly this happens.

“There are a lot of suppliers and subcontractors owed millions as well so I’m sure they will want to know exactly what has gone on here.”