I am suprised that somebody, presented with radar tapes, is going to argue with the CAA. On what grounds?
Sometimes one does wonder though. The other day I was flying N of Brize and on the handover to Shawbury was instructed to turn left urgently to avoid busting Birmingham airspace. I was flying a dead straight track on the autopilot and had two GPSs telling me I was 2nm outside it, and immediately following this instruction (which I obeyed) I got the DME from Birmingham's ILS which together with a ruler on the 1:500k chart confirmed I was exactly where I thought I was! I can only guess that either Shawbury's radar is ~ 2nm out in azimuth at the 35nm distance in question, or they incorrectly determined my track at that moment and thought I was about to bust. If this had resulted in a bust action I would have asked for more than one radar tape.
On another occassion I was flying about 3nm outside Lyneham's zone and was told I was infringing. I turned as instructed, but (as above) this conflicted with GPS+DME so I telephoned their ATC afterwards. They told me they had about 30 microlights bust their zone the day before and were telling people they were busting even when they looked like they might be.