Thank you John.
We've stayed in Bristol quite a few times and (apart from cycling under it) could only see one tower from where we were staying.
On our last evening, I decided to explore to see if I could get a view of the complete bridge.
I was a bit wary around the underpasses with some strange graffiti but came to the above viewing point.
I'd just missed the best light and as I wandered a bit further around the corner, crossing the river, I came upon a couple of Pro photographers who'd been there for hours, apparently on the best spot.
I'll keep it in mind in case we go again.
I've often thought about taking a night picture of the bridge from that area, but as you say, it doesn't look like the safest places to be walking around in the dark. Were the bridge lights on Brian?