The NYMR doesn't have such an exemption. Following the judicial confirmation of ORR's ability to require compliance by West Coast NYMR is having to use door stewards as a tempoarary measure while door locking and droplight modifications are installed.
NYMR has an exemption to Regulation 5 issued 1st April 2023, as per the ORR webpage;
Mark 1 and hinged door rolling stock exemptions | Office of Rail and Road
Applying for an exemption for Mark 1 or hinged door rolling stock.www.orr.gov.uk
This exemption stipulates the secondary locks, stewarding and procedures they need to work with;
Other operators have Regulation 5 exemptions but NYMR are the only ones with the "25mph limit" specified and no need for a CDL fitment plan at present.