As for Vulcan ECM, it was pretty ineffective and had never been properly updated due to cost......
Probably finger trouble by those who flew, as we never considered the "operators" to be the brightest pennies in the bucket.
I have very distinct memories of a snowdrop wagon screeching to a halt and heavy pounding on the underside of the door of our Vulcan, followed by demands from a very distraught chappie with a white hat insisting that we cease doing whatever we were doing as the CO was mightily unhappy at having his evening TV news disrupted, circa late 1964. We always found it to be very effective at ground level, with requests, nay demands, from the Tower that we always, but always, tell them prior to any tests.
.