I’m a longhair and have been for most of my life. I started letting it grow sometime not long after starting secondary school and, as a relatively attentive and well-behaved pupil, the school didn’t raise any objections. I have had a couple of cuts (once, while still at school, for one of the earliest Comic Relief days and later when I embarked on a PGCE) but otherwise it has been largely left to its own devices. Admittedly it does start a little further back than it used to but flows as far down as ever before.
I recently found an interesting online article called “The Truth About Hair“. Fascinating stuff! I’m not entirely sure how much credence I give the arguments (eg. “Cutting of hair is a contributing factor to unawareness of environmental distress in local ecosystems.”) but it makes for a good discussion point. For pogonographers, facial hair also gets a thumbs up as a further set of antennae for discerning the state of the local environment!