The UK Transport Minister, Jim Fitzpatrick, is reviewing helmet law:
Mrs. Curtis-Thomas: To ask the Secretary of State for Transport what assessment he has made of the effects on the (a) rate and (b) severity of cyclist casualties of legal requirements for cyclists to wear helmets. 
Jim Fitzpatrick: The evidence indicates that cycle helmets provide protective benefits in the event of a collision and therefore prevent and reduce injuries. Research suggests that between one third and one half of pedal cycle casualties attending hospital sustained an injury to the head or face. (See DfT Road Safety Research Report Number.30.)
However, we do not know how many head injuries may have been prevented or reduced had the cyclist been wearing a helmet, since we do not know what level of protection is offered in different types of accidents.
The Department has recently commissioned a new research project-looking at a range of road safety and cycling issues. This is now under way and is being undertaken by a consortium led by TRL and including MVA, ITS Leeds, Simon Christmas Ltd, SHM and Arup. It will examine the following topics:
Road user safety and cycling data
Attitudes and behaviours of cyclists and other road users
Bicycle helmets, including an updated evaluation of their effectiveness.
The research project as a whole is likely to be three years in duration, but we are aiming to complete the review of cycle helmet effectiveness by the end of 2009.
If the government bring in compulsory helmet law this can only be bad for cycling in Britain.
It will discourage more people from taking up cycling.
There is no evidence to support the claim that helmets save lives.
[url=http://184.108.40.206/custom?q=cache:Ems1HASicZEJ:www.ctc.org.uk/resources/Campaigns/Helmets.pdf+helmet+law&hl=en&ct=clnk&cd=8&client=g oogle-coop-np][u]Bicycle helmets are only built to withstand the equivalent of a drop from about five and a half feet to the ground[\u][\url]. If a car hits a cyclist at anything more than 25 - 30mph a helmet will make bugger all difference to the outcome.
Basically bicycle helmets are a placebo.