Despite hinting that redundancies could take place in the more centralised functions, such as HR, IT and accountants, a spokeswoman for Alfred McAlpine told B&E online it is much too early to say how hard the company will be hit.

She said: “In truth, what Carillion is buying is a strong growing business and therefore it’s about growth and not shrinking it. Clearly with a merger or acquisition there will always be overlaps, particularly within central functions, but the reaction has been exaggerated. For a start the formal offer hasn’t yet been tabled.”

The spokeswoman said she expects Carillion to make a formal offer by mid December provided the bid remains at 585p a share. She also refuted claims the takeover would be anything like Carillion’s swallowing of Mowlem in February 1996.

She added: “Some of the major shareholders have said they would accept this offer provided it is tabled before 14 December. Then it is up to the shareholders on both sides to approve the acquisitions. McAlpine is a strong business and Carillion is in a very good position to develop those businesses. This is not a Mowlem; this is a completely different situation to buying a company that’s been very weak. McAlpine is a very strong business.”