For those that are interested, I’m thoroughly enjoying my think-tankery, although its one of the reasons (along with the theft) why I’ve not been as regular with my movements here.
One project we’ve been working on is the publication of a book on 14-19 education. We hosted a debate in March with Policy Exchange, which I wrote up for OurKingdom:

The first is the degree to which sixteen year-olds should be treated as adults. Both Sheerman and Rossiter were in no doubt they are still children, and should not be thrown out into the world without sufficient guidance or qualifications. Meanwhile, Willets and Smithers were concerned that sixteen year-olds are already constrained adults, and that attempting to control them to such a large degree was bound to be counter-productive.

It seems to me our muddled sense of when one reaches adulthood is to blame for a lot of unnecessary political wranglings. We allow people to smoke, marry, and condone sex and procreation, from age 16, yet we do not allow people to drive until 17. The voting age remains 18, as does the age at which you can buy alcohol, and (bizarrely, to my mind) we are perfectly at ease in allowing people to choose a religion at age 10, 12 or 14. Surely the mental calculus by which we deem someone responsible enough to do one activity, applies equally to the other activities?
Clearly, all these activities are related to ideas of freedom, choice, and responsibility. Below the age, and you are deemed incapable of making those choices, or wielding wisely the responsibility entrusted to you. In terms of our relationship to the state, it seems reasonable to say that childhood may be defined as the age when the rest of society does not allow you to make your own decisions. Therefore, it is legitimate to constrain the freedom of a child – a second class citizen – from an adult. Above that age, you’re responsible for your actions. Below it, your legal guardian carries-the-can. It would seem sensible to concile the various ‘coming of age’ ages into one, easy-to-remember figure.
To my mind, sixteen seems too young to do most stuff, but eighteen seems to old to prevent someone from driving or having sex. What say we just agree to split the difference, and have a universal age of adulthood at age 17? As with current arrangements, there will always be people who are constrained by this, and others who cannot handle the responsibility. But no more or less than the current situation.
Either that, or why not formalize teenagerdom as a third legal category of person? They could have a similar set of rights to those attempting to earn citizenship. That might help some of those sullen teenagers get a job, and learn proper English…