CMS Cameron McKenna is advising support services company Alfred McAlpine on a proposed £600m offer by rival Carillion.

Alfred McAlpine has been a construction client of Camerons for some time through relationship partner Caroline Cummins, but the firm only began advising on corporate aspects in August of this year. Senior partner Richard Price and corporate partner Gary Green are managing the current transaction.

This follows on from the advice they gave to infrastructure and construction group John Laing last year on its £1bn acquisition by the private equity arm of the Henderson Group.

Slaughter and May partners William Underhill and Kathy Hughes are advising Carillion, together with lead corporate associate Dan Wayte.

In August, Carillion made an initial proposal for Alfred McAlpine of 560p a share. However, this was rejected. A 570p-a-share offer was also declined as it was considered to undervalue the company.

A revised offer of 585p a share is made up of 25 per cent cash, with the rest made up of new Carillion shares. Major shareholders Schroder Investment Management and New Star Asset Management look set to support the proposal. Schroder is also an investor in Carillion.