In the last 40 years some were re-introduced and numbers have steadily climbed, especially on wetland reserves.
A few years ago we saw about 10 from a train window in the fens.
Simple QRP projects, 10m, 8m, 6m, 4m, FT8, 160m, WSPR, LF/MF, sub-9kHz, nanowaves and other random stuff, some not related to amateur radio.
We live about 15km from airbases used by the USAF. In the last couple of days these appears to be an increase in air traffic.