P.S. I myself don't have any problem living in Middelburg only 4 miles from Northsea coast. Even on a portableradio .
Kind regards from a radiofreak PA3ALX Herman Middelburg
This presumes that Droitwich uses directional antennas; which they may, or may not, do. However, it is an alternative explanation to an output-power reduction.
Yet another explanation is that the station's antenna farm is undergoing extensive maintenance/repair during which time they are operating on a backup antenna array with different radiating characteristics.
It may be that the station has dialed back its RF output power somewhat in order to maximize the life of these economically-irreplaceable transmitter tubes.