Retrobrite

[Karlos]

Sunlight and the oxy seem to be the vital ingredients.

It's actually quite interesting. Assuming they got the chemistry right, it's one of the few applications in which hydrogen peroxide is used as a reducing agent rather than the far more common application as a strong oxidising agent (for example, it can be dissociated into OH radicals which are pretty much second only to fluorine in terms of oxidising power).

By the sound of it, the reaction with the bromine-oxygen species present may be similar to the one you get when reacting it with hypochlorite (one method of producing oxygen for small scale lab purposes) in which it is also a reducing agent.

[Karlos]

Actually if you were to try it in the UK you'd likely get arrested as a terrorist.

Well, depending on how south asian / middle eastern you appear anyway. If you are white, you can join a far right organisation and stockpile weapons and explosives and still only be charged under some arcane law dating back to Guy Fawkes (well, not really but still...) rather than the new anti-terrorism laws :-/

Seriously though, the peroxide strength you need for this is available perfectly legally in the UK. Hairdressers buy the stuff all the time.