Particularly during stable, anticyclonic conditions, 'Sporadic E' can cause refraction of VHF signals so that they are heard well outside the intended area of coverage. We used to get a lot of French aeronautical VHF at Brize on one of the normal approach frequencies.
On my drive to AeroExpo last year, French VHF-FM was coming in loud and clear over my car radio! Back in 1967, our school CCF used the '88 set' ex-army radio, which worked on 4 frequencies at around 40 MHz. Because Channel B (41.4 MHz) was close to the BBC TV 405-line Channel 1 signal on 41.5 MHz, a rivet had been installed in the channel selector, giving access only to Channels C&D. On the day of a CCF Field Day, sporadic E was so predominant that Channel C was completely blocked by foreign TV sound, leaving us with only one channel to use.
As the '88 set' pre-dated BBC-TV in many parts of the country, complaints about 'army interference' steadily mounted in the 1950s-60s as the '88 set' began to replace the ancient HF '38 set' at CCFs, leading to the blocking of Channels A&B - and it was very difficult to remove the rivet
!