Glad I went out tonight, despite it being a bit too late for extra nice footage (though the MP4 still did a stunning job in low light). Thinking of it as something of a reconnaissance mission for the proper flight in 4 hour's time I did learn some valuable things about the site, which should serve me well later.
1. I got the actual height of the mast, which is 195 ft, so RTH here should be set to 220 or higher to always clear the tower. This will give me some confidence to orbit around it, where it will unavoidably be between me and the craft for a short time. There are a lot of holes in it and I will have LOS through it - but I am hoping I won't lose signal.
2. There are <8 kestrels nesting on the actual mast itself, so we won't be getting too close to that !
3. 2 Microlights rocked up over the horizon at 100 ft AGL but were just passing through.
4. I could work out exactly where the sun is going to be at 7 am the next day, and can plan my flight paths and launch sites accordingly.
5. I was able to refamiliarize myself with how the whole hill looks from above, minimising my chances of becoming lost when I overfly the individual spars / marylins.
6. There are TONS of butterflies in the long grass all over the hill. It's like that bit in the Hobbit where they all take off from that tree ! So when we do ground level stuff we will follow the paths to avoid mashing them, but stay high enough to keep out of the way of any loose jumping dogs, of which there are likely to be several !