Location wrong on laptops, correct on Android

Your phone is right because it has GPS , but laptops don't, so Windows falls back Microsoft's WiFi-location service. That looks up your router's MAC address (BSSID) in a crowd-sourced database, andyours is wrongly registered in SA11 5LR. That's why nothing you tried worked, the ISP swap, VPN and browser changes don't touch the BSSID lookup at all.

Quick Proof: tether a laptop to your phone's hotspot and check again, If the location correct itself, it's definitely your home router. The fiz is renaming WiFi and adding  nomap to the end of the SSID, which tells the database to drop the bad entry and re-register from the accurate reports your phones are already sending. Did you keep your old router when you switched to Starlink? If so that exactly why the problem followed you across.