A few years back i was paying £30 a year for a council one [West London], I got one closer to home from a charity which was £60, last year it was £80 and this year it's £100.
Most apparently goes on water, but we get little else, security is poor, no toilets [no exactly true].
There's a petition going around asking to be told, but a lot of holders are nervous. The whole site is prime real estate. Several million pounds cash now, or a couple grand a year from some smelly gardeners. Tricky choice.