Reminds me of my own feeble attempts to catch 'the loner'. Just my own name for it not one of those carpy named fish like hogshead or scartail etc. This ws also a ghostie, and typically wary of the ilk. I've always believed fish are much more nervous about attack from above than from below and ghosties are so much easier to spot in a crowd. This one adopted a policy of keeping away from anything else with fins. It would happily mooch about for hours stealing bait just as described. And I too succumbed to the notion that this was in fact a wild pet that I felt responsible for providing with regular sustenance, as opposed to a specimen to be targetted.
Paul is clearly a far superior angler and his cunning tactic of ignoring his beast, and lulling it into a false sense of security and all that, is what led him to the comparative success of actually hooking his target. After 3 summers I came up with the solution of not renewing my club membership and started fishing new waters, for real fish.
I guess it's still doing the same old thing now, and probably at least a twenty, and even more cunning. I could ignore the aggravation that was the true reason for my move, and rejoin the club and seek it out once more, but this May a new 'loner' revealed itself. Again a ghostie, again it left the vicinity whenever another carp turned up.
Not sure how much it weighs is all I can say!