Series One
We first see Avon in the second episode, Spacefall. It appears that most of the prisoners are wearing their own clothes, so we must assume this is what Avon wore around the town. Dreadful, really. Seems that computer geniuses have no sense of style. Still, compared with everyone else on the London, it's not all that bad. Fashion Notes: (Barbara Lane)... had a very small budget, so she sent off to Marks and Spencer's for my trousers and shoes, and spent the time and money desigining a top for me. It was pretty basic, something Chinese, I seem to remember, rather like the Chinese peasants wear, only a darkish colour because she said I was a darkish character.
Even accessorized with a harness and a rather large cylinder, it's not winning any awards. He wears this outfit through Cygnus Alpha, thankfully removing the harness.
In Time Squad, he takes advantage of Jenna's find of a room full of clothes. Sadly, he must have closed his eyes and picked at random. He looks like he would be more at home on the farm than on the flight deck of the most sophisticated ship in the galaxy. Fortunately, someone must have pointed it out to him (probably Vila). We never see this outfit again.
Enter outfit number three. There is a bit of subtext to this outfit. Avon is supposed to be logical and likes computers more than people. So, they added some buttons on the front that made him look a bit like a machine. Not very subtle. And you can imagine that Vila pressed one of them just to see what it would do. Adding to the computer image are the flared shoulders. Makes it look like he has a laptop on his chest. For some reason, he's not allowed full length sleeves. Looks rather like it shrunk in the wash.

He wears this outfit for the next several episodes: The Web, Seek-Locate-Destroy, Mission to Destiny, Duel, Project Avalon, Breakdown. It skips Bounty, but returns for one last time in Deliverance. I'm not sorry to see it go.
The Web is the first instance of Avon wearing the so-called Surface Clothes. The color is not bad on him. I rather liked the surface clothes idea, and was sorry to see it go. Avon only wears this in The Web and Seek-Locate-Destroy.
His next outfit spawns one of those 'I love it/ I hate it' arguments. Not everyone agrees on it. I like the color, he looks good in this green as he did in the blue of the surface clothes. But the silver striping is what is hard to take. If it had just been the neckline stripes, it would have been tolerable. And again, he is denied full sleeve length. Either that, or he should not be allowed in the laundry! This outfit appears in Bounty and Orac.
Last in Series One is the silver jacket. Rather than wear the flattering surface clothes, he dons this rather bright jacket with accentuated pockets. I assume he keeps all his little gadgets in those pockets. Still, the silver of this jacket looks better than another silver outfit he has in Series Two. The jacket is seen in Deliverance and Orac.