NEC ECC: Comparison of Option A v C Tender Prices

An extremely long story short but I am looking for papers, research into comparison of tender prices for Option A and C contracts.

Reason being I have a scheme which is Option C and is currently overspent putting the Contractor into considerable pain. The Client is nervous due to the overspend and contemplating significant omissions. I believe this is the wrong approach and will only worsen the issue. Ultimately anything taken out will need to be done in future so the Client will need to find the money and it will cost more as they wont be getting the pain back.

As a public body the Client is concerned with the political aspect of being overspent so I have shown the savings in £ and p (i.e. they get significant value due to the pain in overspend opposed to doing it themselves later) but to close of the issue and provide peace of mind if I could show them that going Option C was correct and not the cause of the issue (they seem to think Option A would have been better) that would help also.

Basically, I want to show on average Option A contracts cost X% more due to the risk the contractor takes and they wouldn’t have afforded the works in the first place due to budget constraints.

If anybody knows of research or papers (any evidence) that would be much appreciated.

A better place to raise this more discursive question would be on the BuiltIntelligence LinkedIn discussion forum.

Personally, I am not aware of any such research.