We are currently working on an NEC4 ECS scheme in which a statutory body imposed a stop notice, owing to a potential environmental incident. The environmental incident turned out to not actually occur.
The Contractor did not follow suit with their instruction, however we were obligated to obey the instruction of the statutory authority. We encountered delays until clarity was sort RE the incident.
Is this a CE?
I would say that it depends on which party is liable. I assume you (the Subcontractor) are not.
If the Contractor is liable (causing the statutory body to issue a stop notice), you could then have recourse under cl. 60.1 (14), given of course that the Subcontract states that they are responsible for such compliance - otherwise it would have to be proved that it is an implied term in your Subcontract.
If that is not the case (the Subcontract does not state anything in this regard), cl. 60.1 (18) might be of help, although you would still have to prove how they were in breach (which somehow takes you to the above challenge).
Lastly, if neither is responsible (or claims not to be) you could find refuge in cl. 60.1 (19). As this is a matter between you and the Contractor, I doubt that they would challenge the 3rd bullet point (that neither Party could prevent the event) - that would give you grounds for cl. 60.1 (18)!