Always been the rule in our house: if you’re on bike / scooter then you wear a helmet.
Very glad of it too. At Christmas lad lost control of his bike, hit a neighbour’s garage door at about 20mph. Smashed his helmet to bits and put a massive dent in the door (which we need to replace). A&E confirmed he was fine other than a bit of a battering.
Next day, went to Halfords and found a perfect Met helmet a bit like mine that fits a treat and cost £5. At that sort of money, you’d be a bit mad not to wear one.
I do wish I could get a garage door for £5 tho….