At what age do you become an adult in the uk??

I know what you are saying with all the different things at different ages, it is very confusing and even more with the drinking age probably going up to 21, and also laws possibly coming into place about young drivers under a certian age not being able to drive with pengers at night. *rolls eyes* Typically though, you are cled as an adult from 18. This will probably go up to 21 but who needs anything simple in life, hey?!