Last night Kam left a message and today we were able to do this for her in 3 hours.
I wrangled the greenery and Paul finished off with our father's high pressure water blaster. I can assure you, if there are still black spots, they're part of the woodwork. Paul covered every inch meticulously. I realised later that it looks like I've adjusted the filters on the After images but I didn't touch them - that's how bright the wood came up.
We really hope Kam invites us back to do more around the front of the house...
UPDATE 28 Oct: Kam has asked us back tomorrow! We're so thrilled and get to make even more of a difference to her stunning property. She also said word's getting around the agents. I can feel an empire coming on ;-)