I climbed Wee Binnian, in Northern Ireland's Mourne mountain range, a week ago today. Elevation of 745m. The Isle of Man was clearly visible even with the poor conditions. I couldn't see Wales or Scotland, let alone England though.
Peakvisor useful for figuring out what might be visible, this is the view I had:
https://peakvisor.com/panorama.html?lat=54.13982150126688&ln...