I have had this before! First of all and probably most important of all, what are the 'works' in the Contract Data referenced as? If it just says The works are 'the construction of new facility X' with no mention of the design, you can quite justifiably and legally say you entered into a contract 'for construction' only. Consequently, an instruction given for the Contractor to do design "is not in accordance with this contract" (clause 27.3 of NEC3 and NEC4).
That is enough in itself, but would be reinforced by nothing in the original Works Information and the absence of other relevant provisions in the conditions of contract e.g. X15, no PI insurance requirements etc.. Consequently if the EMPLOYER wants you do this - because the PM does not have the power to instruct - then a supplementary agreement needs to be struck, whereby they add i the design and you get added in the relevant provisions.
Having said this, any design in the original WI, you would be contractually obliged to do.
That is enough in itself, but would be reinforced by nothing in the original Works Information and the absence of other relevant provisions in the conditions of contract e.g. X15, no PI insurance requirements etc.. Consequently if the EMPLOYER wants you do this - because the PM does not have the power to instruct - then a supplementary agreement needs to be struck, whereby they add i the design and you get added in the relevant provisions.
Having said this, any design in the original WI, you would be contractually obliged to do.