?
Blue badges last for 3 years.
The restriction is not timed, does not have max. length of stay therefore if you are parked in a BB bay you can do so just by displaying the badge itself.
Therefore 'Meanwhile, I displayed the blue badge between 10am and 4pm, totally forgetting that the disabled bay isn't covered by the same timings. Lo and behold I received a PCN at 7am this morning.'
You removed your BB or was it still visible?
At present, I can't follow the account.
Also, I've never heard of 'a blue badge exemption, but you hold and were displaying one anyway!