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

It's not an instruction, it's a recommendation. The only time, by law, that you have to obey the highway code is when it says 'must'

Sano, my bad, I used 'instruction' when I should have used 'recommendation' or 'suggestion'.

Although see Fred's quote from the Highway Code as well regard should/should not...