Blackwell has been operating in the field of bulk earthmoving and civil engineering for over 50 years and turned over £89m last year, making a £3.3m operation profit.

The Blackwell plant fleet is one of the largest earthmoving and mining fleets in the country. Headquartered in Colchester with five other bases around the country its fleet includes over 50 trucks, around 40 excavators, 15 bulldozers and seven loading shovels.

Hargreaves said the deal, which includes £13m of net debt at Blackwell, would help to diversify its solid fuels and bulk material logistics business into mainstream construction, allowing better utilisation of its heavy plant fleet.

Of a £8.5m net cash payment, £5.25m will be held in escrow awaiting settlement of several historic claims and the sale of two other investment properties with a book value of £6.5m.

Gordon Banham, chief executive officer of Hargreaves, said: “The acquisition of Blackwell extends the reach of Hargreaves into the UK earthworks and civil engineering sector bringing further diversification to the group and offering an attractive return on capital.

“The business is complementary to and synergistic with our existing mining operations and offers flexibility with our existing fleet of heavy plant, providing further opportunities to diversify the group’s operational focus.

“We are delighted to welcome the Blackwell team into the group and look forward to combining our expertise to work with them on the growing market opportunities in the UK, including the enhancement and renewal of the nation’s critical infrastructure.”

The acquisition comes a month after the £662m turnover group announced a cost-cutting re-organisation amid continuing turmoil in its main coal markets.