Oh and just for ****s and giggles, StreetView has been updated to April 2025 for the road in question and there are in fact also two repeater signs with speed camera warning logos immediately before the camera now. No doubt added specifically to help people like the OP who were struggling, so not only did he miss the big signs on Canford Way when he entered the 30 zone, it looks like he also missed the ones right before the camera that he's been arguing should have been in place to stop people getting caught out. Proper comedy.
I've added some markers to help spot them.
(And they're visible in the March 2025 views from the side street too, so almost certainly not added immediately after the OP caught...)