I don't like the idea of an "age of consent", as it suggests that below this specific age, your consent doesn't mean anything as you have no idea what you're consenting to. But I hardly think that's the case.
Having said that, I would support a minimum age at which one is allowed to have sex (just like there's a minimum age that you can drink, drive, watch certain films etc. I don't think the issue is that you can't consent to it because you don't understand it, but simply that you have no right to do it because you're too young.) The reason we need this is because, by having sex, you are risking the possibility of bringing new children into this world, and you have to be mature enough to handle that responsibility.
I'd say that in this country, 16 is a reasonable age limit to set. This is the where compulsory education ends, where a person gains the right to work and earn money, and therefore the minimum possible age where a person can say "if having sex were to result in the birth of children, my partner and I would be perfectly capable of fully assuming the responsibility of raising those children ourselves".