Do they have still image?Watch
If you do something store staff at London Oxford Circus think is bad like return/exchange items and they recognise you year or so later mention you doing it but you never seen this assistant before and they don't take your photo with you knowing. Do they have a CCTV still image of you on the wall in the back room or have the same people working there with good memory and no life? How often do store staff and person in charge change job in that area?
I could be wrong, but I think legally they have to delete CCTV after a month or so, if they've got no reasonable grounds to keep it.
To be fair, if they've got a good memory, its probably an asset to their job, so you can't really slate them for that. However, only recognising someone isn't proof. of anything. At best, they can just keep an eye on you, but they can't get you in trouble if you hadn't done anything wrong on that visit.