Came across this excerpt from
The Enemy is Listening by Aileen Clayton
The principal radio operators involved in this hazardous venture, who spent many airsick hours in a gondola slung beneath the swaying balloon 3000 or 4000 feet above Dover, with air-raids in progress beneath them, were the then Flying Officer Jimmy Mazdon and Pilot Officer Basil Sadler. By coincidence, Sadler was the great grandson of the early English balloonist of the same name. ( He was to be killed later during an investigational flight over Western Europe.) The venture was ...
Maddeningly, I can't find a longer excerpt with what comes after the ellipsis, and the book doesn't seem to be available in electronic format. However, from a review on another site, some info about the author and the RAF Y Service (which was part of or worked in conjunction with the War Office 'Y' Group, I believe), that might aid in finding other references:
Aileen Clayton’s The Enemy is Listening (1980) is part personal memoir and part history of the RAF Y Service in Great Britain and the Mediterranean. The Y Service was the RAF’s contribution to the interception of enemy radio signals, and Clayton was one of the first operators for the service’s program intercepting voice transmissions (in British parlance, voice transmissions were Radio Telephony, or R/T; Morse code transmissions were Wireless Telegraphy, or W/T). R/T intercepts were valuable during the Battle of Britain because they offered immediate information on German operations as or before they happened. But, as The Enemy is Listening describes, R/T interception overlapped with many other aspects of the intelligence war: Bletchley Park and the breaking of Enigma, radar and non-communication signals like guidance beams and navigational beacons, and communications security. Clayton makes it clear that Allied signals security was often lousy, and that her German counterparts must have been gathering an awful lot of information on Allied air activity.
The cover of my Ballantine edition tags Clayton as “the first woman in British history to be commissioned as an intelligence officer.” R/T interception in Great Britain was, from almost the first moment, almost exclusively staffed by the Women’s Auxiliary Air Force (WAAF).
FYI, the "early English balloonist" great-grandfather of Basil is James Sadler who, per the Royal Aeronautical Society, "... in 1810 became the first man to fly over (but then into!) the Bristol Channel after skirting the Glamorgan coast - this being the first balloon flight over Welsh soil."