By the said notice referred to in Clauses 67 .1 and 67.2, and by further notice in writing fourteen (14) calendar days of the date thereof, the Engineer may require the Contractor to assign to the Authority and if so required the Contractor shall forthwith assign to the Authority the benefit of any agreement for the supply of any Plant, goods or materials and/or for the execution of any work for the purposes of the Contract which the Contractor may have entered into.