BBC supporting breaking the law shock!
It's possible that they don't realise that they're breaking the law. In most of the country, there is no speed limit for bicycles, and they may not realise that the 20mph speed limit in Richmond Park applies to
all vehicles.
Of course, claiming that he was going that fast isn't proof that he was, although it's probably not a wise move to claim you've done that.
They didn't claim at any point that they had official permission to go that fast, and I'm not sure how you would go about getting the bylaw suspended. I would imagine if you did somehow get permission to cycle around the park that fast, they'd probably close it to motorised traffic, which it clearly wasn't.
I think the Parks Police got absorbed into the rest of the Met, has anyone thought of sending them the link?