They don't put a kit mark on new helmets which conform to the EEC standard, you will find a tab in the helmet bearing the require standard.
The visor markings are as follows.
Motor Cycle (Eye Protectors) Regulations 1999
The Personal Protective Equipment (EC Directive) Regulations 2002
€¢ Eye protectors which bear British Standard approval marks (4110 - X, XA, YA or ZA),
€¢ any other equivalent standard accepted by an EEA state and marked to indicate that standard,
€¢ conformity with the requirements of Council Directive 89/686/EEC as amended (goggles),
€¢ those which conform with ECE Regulation 22.05 including the approval, marking and conformity of
production requirements of that Regulation,
€¢ eye protectors first used before 1/4/89 with lenses that are designed to correct a defect in sight and
which transmit 50% or more of the light and do not fly into fragments if fractured.