I wasn't aware of MI8's involvement in finding navigational beams, a subject I have been looking at in recent months.
I started out looking for an Operations Record Book for No. 80 Wing (which did the detecting and jamming for the RAF) and didn't find one but a search of the catalogue for relevant code names (e.g. "HEADACHE") gave better results (
see here).
I guess you've tried searching via Radio Security Service and RSS? There seem to be quite a few occurrences in the Government Code & Cipher School files — although that could even be one memo on a thick file.