There's plenty on the footage but I suspect its quite biased. I'm assuming it was generally a black music event with mostly West Indians there, but with small groups of skinheads dotted about.
As for Jon Woods, its strange the way its gone. I can't find any sign of Jon Wood before 1970. They're massed produced colorful shirts for the big skinhead market of 1970. They're not bad, but differ quite a lot from the average British made 'skinhead button down'. Second button's quite low so the collar sits quite wide (not unlike an American shirt). (they did do a high second button one as well but this is a lot less common). Sleeves are baggier (than Ben Sherman, Brutus, Jaytex, Arnold Palmer etc etc) and the short sleeved version has a cuffed finish with vee cut but with a single button at the top of the vee. The same sleeve appears on Slim Jim and Mr Pigalle (off the top of me head - sure I could find a few more in me wardrobe), unlike the Brutus style one which was copied by many more. Check's twisted on the top pocket (always the mark of cheaper manufacture). Full back pleat with 2 darts, 3 button collar. Collars are a little longer (3 3/4inch, as opposed to the 3'n'arf inch Benny collar and 3 3/8 Brutus) and the kneck sits slightly higher, again subtley changing the look from say a Benny. They did various bright checks (as well as plains but very rarely stripes). Later they did many designs of Penny collar, with buttons galore - another story. They also did some of the same shirts sold under the Permenant Press and Man Alive labels (but from the same pattern). They also shared cloth with Jaytex at one point (from a standard Jaytex pattern).
They've become the modern day skinhead staple, with the big, bold orange, green or blue checks being very popular (and changing hands for up to 200 quid on ebay). "The orange Jon Wood" is in most skinhead's vocabulary nowadays.
I've had dozens over the years, proof in itself how common they were originally and despite having a few pics of original skinheads wearing them, I wear them now and then but in my opinion, its far from Sunday Best..
I'll stop before I go into too much (irelevant) detail but I hope that helps.