Ours were all trackable to excessive water pressure from the water company causing a "cascade failure" of small leaks to be chased around.

Oh, how frustrating - I've been warned that can happen with an increase in system pressure - the water constantly exploiting the weakest link!

Super nice view from your roof, though!

Thanks! I need to find a way of making the rooftop usable but planning permission is tricky because my neighbours have a bedroom window there! The view from our upstairs is good too so we don't need to be greedy 🙂