When you are close to a low frequency radio station anything is possible I guess. I used to live less than one mile away from an AM radio station antenna. That doesn't mix up well if you want to become an electronic engineer or compose your own electronic music. ;-)

The Telecaster guitar and bass used would be my #1 culprit on introducing noise since pickups are virtually antennas. Mike Oldfield even had added an extra high gain single coil BL pickup to his '66 Tele. If you don't gain stage or ground properly the mics that were used for the acoustic instruments, they could have also captured RF noise easily, even if they had a heavy metal housing that acted like shielding. Some Farfisa organs are also noticeable noisy, although I don't know about their EMI or how banged up was the one used for the album that belonged to David Bedford. The electric piano used was a Rhodes, and those were built like a tank. Finally the tracks were overdubbed over and over. This would in all likelihood have attenuated both the audio and noise, but using a mixer or a tape that is susceptible to interference means that you have more chances of capturing noise at some point in the recording. I guess we will never know for sure.

Anyway, it adds to the mystique of the record.