On an Option A contract the contract contains 40+ Z clauses. It is a contract 2 years on the ground, 1 year in delay and 50% above budget, with the majority of delays and additional costs around design. One of the Z clauses puts design responsibility of the ‘Base’ design onto the Contractor in terms of design development and responsibility. Within the Employers Works Information though, the Contractor’s own list of tender exclusions has been included, of which one exclusion is for responsibility of the design. Another key exclusion by the Contractor removes the Contractor from certain risks identified within the project risk register stated as Contractors risks, this had been appended to the contract data. My question is where does this ambiguity stand as I am unclear where in terms of hierarchy do these documents sit.
Here is a link to an article I wrote many years ago on precedence / hierarchy of documents under NEC : http://www.jonbroome.com/getattachment/44704d3b-547d-4bd9-a278-b40389ffcc58/Is-there-a-hierarchy-of-documents-under-the-ECC.aspx
Without knowing the details, the Z clauses stating the Contractor has responsibility for design development would have precedence over the risks stated in the Employer’s Works Information.
However, in cases like this, my experience is that the devil is in the detail of the precise wording, both of the Z clauses and the WI, and of what happened in practice i.e . who did / didn’t do what and when. E.g.if the Accepted Programme said that the Employer supplies information to base your design on and they did not do it, then that is probably (depending on the Z clause wording) a compensation event.
An excellent article Jon, well worth a read. One further point as a note is, as you say, the devil is in the detail of the precise wording. On first glance there may appear to be an ambiguity or inconsistency between the documents, but often when you analyse and examine the wording in detail you will often come to a different conclusion. This is especially so when reading all the documents together, which I appreciate can be a little daunting, considering the amount of information that is often included, but absolutely necessary to really understand the contract.
See also the recent case of RWE Npower Renewables Ltd v J N Bentley Ltd  EWCA Civ 150, 19 February 2014 which was heard at the Appeal Court. The issue of order of precedence was discussed. Note also that this was an NEC3 contract.