Bubu hatched around the 17th of April 2010. This makes him almost 4 1/2 years old now.
He started biting me, sometimes he's got proper hissy fits and attacks my hands. I try to ignore him hoping this is a phase and will go away with time.

Is 4 1/2 yo the infamous teenage stage? Isn't it a bit late? He has never done anything like that when he was younger, now he comes to me for scritches and then proceeds to bite me. He doesn't attack me like dive bombing, just sits next to me and then as soon as I touch him he becomes a little fury.
Very sad and frustrating
Is there anything I can do apart from ignoring the biting?

He is also a little terror with the other birds; he gets annoyed with everyone very easily and will shoo away the birds who, in his opinion, are someplace he thinks they shouldn't be.

I would consider the teenage stage to be when they first hit puberty, when they're less than a year old. But a bird can get hormonal at any age, which usually means nasty aggressive behavior in males. Hormone control techniques might be helpful: http://www.littlefeatheredbuddies.com/i ... mones.html

Preventing biting is a better tactic than ignoring it. Keep an eye on his body language and don't touch him if he starts making threats when you raise your finger. To help put him in a good mood, try offering him some treats to eat from your hand before you try to touch him, or just sweet talk him for a while as a warmup before you go for the scritch. You basically want to seduce him into it instead of assuming that he's ready right at the start.

If he's bullying the other birds too badly you can move him away from them, using a stick for the step up instead of your hand so he doesn't bite you.

He doesn't give any warnings at all. He might come to me, put his head under my hand for scritches, and after 5 seconds bite me, just like that. I don't know how good it would be to retreat my hand at that point. I usually leave it there and wait for the fit to end.
He is in constant battle with Keith over scritches. He is extremely jealous so I try to give him at least one hour of one-to-one time, more if I can. His idea of bliss is him on my shoulder while I sit still like a statue. I move, he bites my ear lol
The other birds take it with good humour and just move or, if they are not in forgiving mood, will open their beak, and when that happens he backs off immediately.
He is not vicious, just in a constant bad mood. He is definitely hormonal, Darcy and him are a hormone bomb. I will try move their cage where they can have more darkness and silence.
I was really hoping it was an age stage that would resolve itself.
I will try with treats but I am not sure he'll react to that. It seems to me that he got worse and worse since last year. At the time he was nice with people, now I need to hide him if I have visits or the occasional repairman. A crying shame, he was such a solar character

That's how Pippin behaves when she's stressed out--it's like she wants to be cuddled and petted, but she can't relax enough and bites the instant you don't scritch exactly how she wants. Could something (aside from the obvious hormones) be stressing him out?

Moving him away from the other birds to somewhere calmer sounds like a good idea. He might be feeling like he needs to fight off all these other birds to have you and/or Darcy to himself, or having all the energy of the other birds might just be winding him up and he has a hard time calming himself down. Destructive toys could also be a help if he likes them, so he can exhaust himself.

Could it be getting worse because of the changes you have had to make to do with the council inspection?

Birds do bite for a reason but we don't always know what the reason is. Every time he bites you, first of all withdraw your hand - there's no profit in letting a bird gnaw on you. Then think about what happened just before the bite to see if you can identify what triggered it. Is another bird approaching, particularly Keith? If so, that's probably the reason. I used to have problems with Vlad biting in the middle of a scritch, apparently out of the blue. But when I started paying attention I realized that he did it when another bird approached. He was afraid the other bird would be jealous and attack him, and his fears were justified. Now I pull my hand away when I see another bird approach. I'm not always quick enough but there's a lot less hand-biting now.

Biting during a scritch is a "stop scritching" signal and birds do it to each other when they're allopreening. There are other things that can cause it, for example some kind of disruption in the room that makes the bird think he needs to be alert for danger. I've heard of birds that would bite during a scritch because another bird in the room squawked.

surely the disruption in the bird room made everyone edgy.
It's actually getting even worse now. Today I had to completely dismantle the bird room, there are broken tiles containing asbestos and tomorrow the council contractors will be here to remove the broken ones and cover the floor with a layer of cement.

So everything is gone now, and I moved all the birds in the living room where I will be staying all the time so at least they know I am still here with them. They actually seem a lot calmer now.

Once the bird room is back up, I will keep Bubu with me as much as I can, cage and all, and see how he responds to being away from the flock; he might calm down and if he does it's definitely a problem of presence/interaction with the flock.

Ideally I would like to keep him away from Darcy too since they feed nervousness to each other, but that's gonna be complicated and I am not sure it would serve to anything apart from making Darcy miserable.

Is it possible that there is something in the bird room that makes them nervous? I was thinking of adding curtains, maybe all the activity in the garden (cats - rarely, other birds, people, insects) makes them feel unsafe and that influences Bubu's behaviour as well.
If I am with them they are ok and don't scream, when I'm away they are very unsettled. It could be just them wanting me as flock mate, or maybe they don't feel ok to be left alone in there.

Uchh I'm sorry things are getting rough lately. Just remember, it will get better.

Thank you Baruch, I keep telling myself the same thing. Maybe it's a good thing that I have to redo everything now, who knows.

If they're seeing a lot of cats in the garden that could be a problem. My birds freak out every time they see a hawk outside (which is daily) and sometimes I have to close the blinds to calm them down.

It's also possible that it's because they can tell you're upset (with good reason) so they're getting upset too. Birds are very sensitive to our emotions, and when we feel disturbed they know something is wrong and it disturbs them too.