The Enquirer understands that all sites were told to down tools this morning by administrator BDO.

The restructuring specialist confirmed that Hewlett Civil Engineering Limited, Hewlett Rail Limited, Hewlett Plant Hire Limited and Portford Homes Limited are all in administration.

The companies undertake civil engineering for commercial projects and construction related training in the following sectors: highways, defence, rail, residential, renewals, power and process.

The companies operate from a head office in Leeds, two additional regional offices, a further two training sites and third party contractor sites.

Collectively, the companies employ approximately 300 staff based at the above locations. No redundancies were made immediately following the appointment of the joint administrators.

Paul Bates, BDO business restructuring partner, said: “The companies encountered financial difficulties as a result of the challenging economic climate over the past few years.

“Turnover has fallen from about £62m in 2009 to about £42m in 2012. Regrettably, this has meant that the companies are unable to continue to trade in their current form.

“At the moment we are conducting a thorough appraisal of the companies to determine whether it is viable for the companies to continue to trade during the administration process.

“We are also assessing the potential for a sale of all or some of the companies on a going concern basis.”

The family run business was set up in 1987 and its client base included Scottish and Southern Energy, Network Rail and Balfour Beatty.