Open All Hours : S4 E5 Happy Birthday Arkwright

https://www.imdb.com/title/tt0074036/

Nurse Gladys plays a trick on Arkwright, helped by Granville. They persuade the shop-keeper that a man representing the Good Shop-keepers' Guide is in the area, awarding bonuses to shops whose staff show extra courtesy. She then dresses as a male shop inspector and visits Arkwright's shop, where she is greeted with unusual civility.