Colour Quest managing director Tyrone Spence said structural engineers were assessing the damage to the firm's premises in Maxted Road, one of the worst-hit areas.

Spence said that the print firm was due to be visited by manufacturers of all of its equipment.

"They will assess if the equipment can still be used or will need to be repaired," said Spence.

The company's premises have been made secure while assessments continue.

Despite sustaining significant damage to its offices, also in Maxted Road, Apex Digital Graphics' workforce was able to return to its premises on 15 December.

However its Ryobi demonstration centre (pictured) will take longer to repair.

Colourbyte director Tim Stockley said his workforce was now in the premises and business was returning to normal.

A clear-up operation was underway, with repairs being made to the firm's twisted roof.

"It does make you think what you would do in an extreme risk situation," Stockley said.

Another plant to sustain damage was Pitney Bowes' document solutions centre, situated just over 700m from the blast.

The plant, which provides print, fulfilment and mailing services and has 60 staff, suffered some structural damage.

"A disaster recovery plan was put in place, which involved the transfer of work and some staff to other sites in Hemel, Staffordshire and London," said managing director Richard Thompson.

A number of printers and equipment suppliers in Hemel Hempstead were affected by the explosions at the depot on 11 December. The fires continued to burn until they were either extinguished, or as in the case of one fire, left to burn out after it re-ignited.