My best mate is male, we have got on for years.

We do have a bit of a past, when we first met he admitted he liked me and we ended up kissing. However, we agreed to just keep it as friends.

Recently, he has changed towards me. He is flirtier and always teasing me, making me laugh, trying to chat to me (making sure we are in the same room). He seems jealous if I look at a lad, even if it's a celeb in a mag. He'll mess around with me, i.e. grabbing my hair pretending to cut it, pushing me softly in the back to make me laugh, silly voices even trying to copy my voice/accent. We went on a night out a little while ago and I could see him looking at me out the corner of my eye, all night. Even my other mate commented that my best mate went quiet if another lad that he didn't know come over to talk to me.

This is what makes me unsure, sometimes he says things like "Ooh shes nice" and "You can pull someone for me." Am I just becoming like one of the lads to him?

I need help, I do like him but I don't know what to do. Its quite funny in some ways, I am usually the person that gives the advice to my mates about relationships. However, this one is tricky. I don't want to lose him and he will be moving away soon, I don't want him going and not knowing either.

Please Help me!

Sounds like he may be starting to have deeper feelings for you but not sure he should take it to another level. Just keep being the best friend he ever had and let him go at his own pace.
It is better to keep him as best friends for as long as you can than jump ahead into something more and possibly losing a friend and a boyfriend all in one. So just take it at his pace.
If 'n when his feelings get too deep to stay at friend level you will know and make sure he discusses it with you rather than just kissing or whatever and assuming it has become more than it is.