Going by their own cancellation policy, they should cancel first time offences for blue badge users. So I don’t get why you’d need a separate SYL policy?
To quote their policy:
“When in a place that requires a permit, scratchcard, pay & display ticket,
Disabled Person's Badge or any other item to be displayed in the vehicle, that
item must be displayed so that all details are clearly visible. If a CEO cannot see
all the details then a PCN may be issued. It is not a defence against a PCN
simply to possess an item. If the item can be produced with the representations,
however, and was valid at the time of the contravention then the Council will
consider using its discretion to cancel the PCN. In general, discretion will only be
applied once.”
So the blue badge was valid at the time, only mistake being clock missing. Only contention would be if more than 3 hours of the allowed time had elapsed. However, since the PCN was issued at 1927, this was only 27 minutes into the allowed 3 hours, using common sense you’d comfortably say that 3 hours hadn’t been violated.
So the council could easily have cancelled had they implemented their own cancellation policy.