You are legally responsible for the actions of your staff so if they sell to an under-age person you could be prosecuted.
All staff selling age-restricted products must have an understanding of the law. Training must be given to all new starters and refreshers given to all staff on a periodic basis. Talk to them about proof of age cards and the ones your company will accept and encourage them to take time to look at their customers.
Training should be recorded and must cover:
- knowledge of the law
- awareness of company policies and procedures
- advice on handling refusals
- as part of your procedures you should ensure that employees sign a declaration or pledge sheet, to say that they have received training and understand the legal requirements imposed upon them and your business.
If appropriate there should be a regular staff audit to ensure that they are up to date and continue to understand what is required, you may even wish to do your own test purchase exercise.