Can't lose?
OP, despite facing towards the B283, you turned in from there because the road behind you is closed and therefore you couldn't access from this direction.
There is a traffic sign within your vicinity - on the balance of probabilities, GSV shows this (the Dry Riser does rather pin-point its location) which you were obliged to discover and comply with. It's not hidden.
You say the CEO referred to a 'controlled zone', but you're unable to produce independent evidence in support. It is wholly permissible to have stand-alone waiting restrictions within a CPZ, although in this case there isn't evidence that there is a CPZ.
You imply that you spoke to the CEO after the PCN was issued, if so what difference would their comment make to you because you were already in contravention.
I cannot see how the quoted cases, which refer to moving traffic contraventions and therefore different legislation, bear upon your case. CEOs are not David Baileys, if because of the relative positions of the car and sign it's not possible to capture in the same shot other than possibly side-on and therefore unreadable, this would not IMO invalidate the PCN.
But they'll be other views.
