I've been friends with this guy for about 10 years (for the last 6 I have been in a serious relationship with someone, well actually since I've known the guy I've probably been dating someone - but I've always held a soft spot for him - wrong I know but I can't help it)

I don't understand why you should see that as wrong.  When you are going out with someone, it doesn't mean you can't fancy anyone else, it's just wise that you don't get involved with that someone else until you are single.

quite a few people have said that he like(d/s) me because we were so close.

If quite a few people notice it, then that should tell you something.

I was never sure, I mean we hugged but we hug all of our friends, and whenever I was upset he was there for me.

That is a very solid sign from a bloke.  To be there when you needed a hug and to be able to discuss your problems with.  It is the sort of bloke you need to spend the rest of your life with.

About 2 years ago I broke off from me friends (I had a miscarriage and got depression - but didn't tell anyone) and when I saw him again, the first thing he said was that it must be fate because he doesn't normally go out on that night - and then he went to hug me (but I was little reluctant, because I was still feeling wierd) and he said 'oh come on its me) which was probably just an 'we're old friends thing' . I'm really unhappy because I was so anxious about going out that, even though he was really trying to be friends for about the next 10 times I saw him, I just kept up that barrier - so now we have drifted apart again. BUT, he's working in my local and I swear that, aside from the standard 'how are you doing stuff' he keeps on looking over at me. then I started to think back and there!

There must be something there, if he keeps looking at you.

are some times when he's said some wierd stuff, like when 'you could be mine' came on he said that it was our song, and I don't know, just silly things...like when I made a joke that no-one would want to see me without makeup - he said that I looked beautiful without it, and when I was upset he called me one on prettiest females he knew, he seems to point out stuff like remembering my birthday and once when he was djing he and it was just us two he played underwater love, and I keep on accidentally making eye contact with him, he's always been really protective off me. I really don't know what to think, because I'm gutted that I blocked his attempts to become close again,

He obviously hasn't given up, so I don't see why you should be gutted that you blocked his attempts to become close again.

and I'm completely in two minds about whether he liked me or not because all of that could just be a long term friendship/brotherly closeness thing, but as one of my friends point out - I've always had a boyfriend since we've known each other, and even my mum (who came to the pub one day) said he kept looking over at me - but then again mums' like to think their daughters are attractive don't they :P.

But mums also have more life experience, and are in a better position to be able to judge whether a bloke fancies her daughter.

Because we're not close anymore I don't even know how to say 'oh hey, please ignore the last 2 years and me being off-ish, I was nuts'

I don't see why you should make this an issue, if you want to get to know him again, then make an effort to get to know him again.  He obviously still wants to know you even though you have been off with him for the past 2 years.

Sorry for this being so long, I'm just so confused, I feel like he likes me but that might just be wishful thinking.

how can I tell whether or not an old close friend (who still seems willing to be friends) actually fancies me or not?,

I think your next stage is to get to get close to him again.  Hopefully beyond that, he or you will end up making a move.  The important thing is to not jump in and be pushy.  There are two steps 1) Get close to him again. 2) Then hopefully it will become obvious about whether you have any long term future and one of you will make the move.

and maybe the old signs that he did don't matter anymore because I've been with my boyfriend for so long he might have given up - but I swear I still get that 'hes looking at me' feeling

He more than likely is looking at you, but he is less likely to make a move if you have a boyfriend and he is even more less likely to make a move if he hasn't got to know you again.