Remember kids... always wear a helmet. (The almighty bikeradar helmet thread)

That's not really a fair reflection of the debate. Of course, there are dickheads in parliament, as there are outside it, who think helmet compulsion is a good idea, but the debate contained both the opposing views* on helmet compulsion and plenty of comment on the points you raise.

*Obviously, as this was parliament where every discussion is weighed down by the dogma that government can solve problems, only the statistical public benefit counterarguments were put. The thing which always seems to be conspicuous by its absence in parliamentary debate is what one might call the Cato viewpoint - individual liberty, limited government, free markets and peace.

Individual liberty - helmet choice is a matter for the individual,
Limited government - there is no public good to be had by compulsion because the effect of helmet choice bears principally on the individual,
Free markets - the costs and benefits of helmet use can be priced individually by each market actor without state intervention,
Peace - compulsion degrades society because all impositions of government invoke dispute.

Good contribution fro Lilian Greenwood mentioning the decline in cycling in countries where helmet laws have been introduced.