OP, in the absence of any up to date photos from you we're left with the council's and GSV, and the hotel cum restaurant.
What does GSV show?
3 separate parking places opposite the combined frontage of the hotel and restaurant.
The council's photos appear to show you parked in the third of these in which there's a post with a one-way sign and a traffic sign at right-angles stating 'pay here at machine'. They also show a suspension sign with what appears(when compared with GSV) a telephone box and a payment machine. This places your car in the same parking place opposite the restaurant.
My point about this set up is that the suspension sign does not have three sides, only a single side facing the road and that in combination with the 'pay her sign' which is visible without having to look at anything from the road a motorist could park, approach the machine, see the 'pay here' sign, pay and leave without even having their attention drawn to the suspension sign. Other than their curiosity being aroused by the back of the sign there was no reason for them to look.
Is IMO, a plausible line for a defence.
Why didn't the council place a regular-and for all I know the only mandated form of sign with 'wings'?
Was there any indication on the machine itself that there was a suspension?
See what others think.