Beagle me old mucker Hardly a nice reasoned response mate.
Do a search ... the phrase TWATCO appears regularly when BEagle is discussing ATC. Maybe one of us stole his girlfriend or something in years past
Slippage of his picture was entirely possible and in any case he was probably using secondary or processed-primary returns.
Slippage ? Now how does that happen ? It's not like we use a Flight Management System to determine radar head position and so could suffer map slip, nor do ATC units move around (ships and rigs excepted ... and maybe Amsterdam Tower in high winds by a few feet !!).
Processed returns might cause a slight difference in indicated radar postion by up to 0.1NM, especially with track smoothing in operation, but if you were flying in a straight line this effect is unlikely.
I think the path offered on the Flyer Forum is the best course of action in your case. If it had been a 'bang to rights' infringement then I suspect Luton would have filed a CA939 (Breach of Legislation). The fact they have not done so means there is probably not proof beyond reasonable doubt that any alleged infringer was actually you.