I wish I knew the answer, as we have the same problem at our house in Buxton.
There is something odd about the microclimate, just around our property, as first algae, and then moss grows rapidly.
It's not just the crevices like roof rails and around lights, but even over the vehicle paintwork after a month or two.
It even grows on the windscreen wipers
The tarmac and concrete paths and drives get covered in no time at all.
On these, I've used sodium percarbonate crystals, often known as oxygen bleach, to quite good effect as a moss killer. I can't use anything toxic, as our groundwater drains into next door's pond.
I'm reluctant to try it on metalwork though, as Landrovers corrode fast enough as it is.
Do we have any chemists amongst us?
Bill