Perhaps there can be more than one extreme aberration.
I've just joined so that I can report a male with virtually no white on the upperside, seen in flight on Sunday afternoon some 3.5k NW of Lady Wood at the entrance to Old Dry Hills. It circled me a couple of times at waist height, threatened to land on my car then climbed swiftly and disappeared over the trees. No chance of a photo but no doubt that it was an extreme aberration. The brief glimpse of solid purple as it passed close by was stunning - an image I'll never forget!
I have reported to Doug Goddard (Northants recorder) who hopes to check the area today.
Colin Bowler (aka Slow Right Arm)