Radio North 846 from the Irish/Northern Ireland border area (Donegal?) is a consistently good signal into London these days. It is audible from mid-afternoon and as late as 09/10.00 in the morning.
Here’s how it was sounding this early evening just after 18.15:
If YouTube has blocked the video due to the brief Glen Campbell song then try this one:
The signal is so consistent it is my MF beacon with which I test the Flag antenna and various baluns.