Exemptions
Drivers of the following vehicles will not be required to hold a Driver CPC:
1.a vehicle with a maximum authorised speed not exceeding 45 km/h
2.a vehicle used by, or under the control of, the armed forces, a police force, a fire and rescue authority
3.a vehicle undergoing road tests for technical development, repair or maintenance purposes, or of new or rebuilt Vehicles which have not yet been put into service
4.a vehicle used in a state of emergency or assigned to a rescue mission
5.a vehicle used in the course of driving lessons for the purpose of enabling that person to obtain a driving licence or a CPC
6.a vehicle used for non-commercial carriage of passengers or goods for personal use
7.a vehicle carrying material or equipment to be used by that person in the course of his or her work, provided that driving that vehicle is not that person's principal activity.
An example of a driver under exemption vii (also known as "incidental driver") would be a brick layer who drives a load of bricks from the builder's yard to the building site and then spends their working day laying bricks. In this case, driving a lorry is incidental to their main occupation.
However, drivers can move in and out of an exemption, depending on the circumstances in which they are driving. For example, a bus mechanic would be exempt while driving a bus to check that it had been repaired, but would need to hold a Driver CPC if they also drove a bus on a passenger carrying service.
i believe you employer is using this exempsion rule for his reasoning
4.a vehicle used in a state of emergency or assigned to a rescue mission
http://www.centraltra...co.uk/driver-cpc.html
is where this info is from .