There's no law which compels cyclists of any age to wear a helmet in UK.
However, it's obviously dangerous to cycle without one, and the Highway Code suggests all cyclists wear a safe and well-fitting helmet regardless of what the laws says.
The UK has about 100 cycling deaths a year. That might sound a lot but it’s not, when you compare it to the 60,000+ deaths attributable to inactivity and obesity.
If you mandated helmets and saved (let’s be conservative) 10 lives as a result, then that would crudely be wiped out by a 0.03% rise in inactivity deaths.
Unlike driving, cycling (like walking) is active travel. It has inherent health benefits simply arising from the act of doing it. Any legislation controlling it is likely to create more friction and discouragement, and hence reduce overall levels.
It’s also worth bearing in mind that safety is a well-studied topic, and hence we know that protective equipment is the least effective safety measure in a hazardous environment, and hence should be the last resort. This is neatly illustrated in the Hierarchy of Hazard Control:
Finally, almost 50% of severe head injuries in the UK happen in cars. If the motivation of those advocating for cycle helmet legislation is public health improvement, then why not start by mandating helmets for car occupants? It’d save many more lives, so what could the motivation be for not starting there?
There has been much discussion on this and there is a strong opinion that if wearing helmets were to be made compulsory then it would potentially discourage people from cycling. Having said that it is common sense that you should wear a helmet when on public roads which in the U.K. do not have very much in the way of separation between cyclists and other road traffic unlike many European countries where there is a much greater level of segregation for example protected cycle lanes which are physically separated from the carriageway. In the U.K. cycle lanes partition towns tend to be almost random with cyclist forced to return to the main traffic flows for junctions, things are slowly improving but there is a long way to go. Even low mechanism accidents and collisions can benefit from wearing a helmet, I know of one person who simply lost their balance while stationary, fell and hit the side of their head which permanently damaged their hearing in one ear - a helmet would likely have prevented this. A helmet can make the difference between an incident that you can walk away from to one with a more serious outcome.
Wearing a helmet has obvious benefits and the approach is one of Education rather than legislation, unless you can identify individual cyclists by some sort of registration then this law would be impossible to enforce, a mere handful who happened to be stopped while riding helmetless would be prosecuted while the great majority would simply ignore the law; the police have far better things to do than book cyclists for minor offences many of whom already hold the view that they are somehow exempt from the road traffic law in many other areas such as red traffic light and not riding on pavements. Whether with the increased popularity of cycling there may have to be some legislation remains to be seen after all if the state pays for you to be put back together after an accident then it may reasonably expect you to take sensible precautions to minimise injury as happened with motorcycle helmets.
What equipment is needed to be fitted to a bike to make it legal to ride on British roads?
Your bike should be in good condition and adequately maintained and it is not compulsory to wear a cycle helmet in Britain. Essentially the only items of equipment that must be fitted to legally ride a bike on British roads are brakes and lights.
The Pedal Cycles (and Use) Regulations 1983 only stipulate that every pedal cycle (the rules are slightly different for electrically-assisted bikes) should have two braking systems (one can be a back pedal-operated rear brake). The Road Vehicle Lighting Regulations 1989 (amended several times) stipulate that bikes ridden at night must be fitted with white front and red rear lights, flashing or steady, as well as a red rear reflector.
All bicycles made after October 1st 1985 must also be fitted with amber pedal reflectors (on each pedal) when being ridden on a public road between sunset and sunrise, although fitting such reflectors is almost impossible with many ‘clipless’ pedal styles. It’s important to comply with these regulations as any slight illegality with respect to your lights or reflectors may be regarded as contributory negligence should you be involved in an accident at night.
Bikes have to be fitted with bells while in the bike shop, but there is no legal requirement to fit or use them once on the road. The Highway Code merely suggests that cyclists ‘should be considerate of other road users, particularly blind and partially sighted pedestrians. Let them know you are there when necessary, for example by ringing your bell.’ Any other ‘audible warning’ – horn, rattle, duck call or the human voice – would do.