Speeding fine for Richmond Park cyclist riding at 41mph - is penalty lawful?

A cyclist in London’s Richmond Park has been fined for riding his bike at more than twice the speed limit – just four months after a Royal Parks spokesman said that speed limits in the places it manages don't apply to cyclists.
 
Rory Palmer pleaded guilty to breaking the park’s speed limit of 20mph on Sawyers Hill on 2 January this year, reports This Is Local London.

Wimbledon Magistrates’ Court was told that police officers spotted the cyclist overtaking cars as he headed towards them from the direction of Richmond Gate. The officers were conducting an anti-speeding operation close to Barn Wood, said to be busy with vehicles at the time in question.

The rider, admitted when stopped that he had been travelling too fast, telling officers, "I know, I'm sorry."

Mutahir Ahmed, speaking in mitigation, said: "Cycling is his hobby and he understands how dangerous it was. It was a windy day and he was coming down the hill.

“He did realise at the time he was going above 20mph but did not have a speedometer."
Magistrates fined him £65 plus a £20 surcharge and he was also ordered to pay prosecution costs of £65.

BBC broadcaster Jeremy Vine was stopped for 'speeding' in Hyde Park in November of last year. A Royal Parks spokesman subsequently told him that there was no speed limit for cyclists in Hyde Park - and, by extension, any of the other 10 parks or open spaces it manages in London. So was Rory Priors fine lawful?

What do you think? should speeding limits apply to vehicles such as bicycles that dont have numberplates or speedometers?

Surely if you don't admit fault under these circumstances something to do with "not knowingly breaking the speed limit" would come in to play

Maybe cyclists should start investing in camera detectors as well as car drivers, then at least you would get alerts and it would tell you your speed!