Answered: NEC3 ECC: Impact of quantities being stated in the Works Information when using an Option C

The definition  of Works Information 11.2(19) is information which either
 - specifies and describes the works or
- states any constraints on how the Contractor Provides the Works

In this instance because the quantities are stated in the Works Information then a change in quantity is a change to the Works Information and the Contractor can notify a compensation event under clause 60.1.1 change to the Works Information.

The usual rule is that in ECC main Option A and C the Contractor takes the risk for the quantity of work required. However if quantities are stated in the Works Information and these are incorrect then this is a change in the Works Information and a compensation event under clause 60.1(1)

I would agree with your comment that if quantities are stated in the Works Information and these are incorrect then this is an Employer risk.

So if I were the Contractor I would notify a compensation event under 60.1(1) for a change in the Works Information.