Memories of Linda Smith

A welcome repeat on the radio yesterday of a comedy programme written and performed by the lovely Linda Smith. A woman goes into a shop and questions the manager: “Is this CD genuine whale song?” “No madam”, he replies, “It’s a cover by a tribute band of dolphins, signature tune, ‘Hey, Hey, We’re the Minkies …’”
 
Asked once in an interview where she grew up, Linda replied that it was a dreary place on the Thames Estuary in Kent called Erith. "Erith wasn't twinned with anywhere," she said, "but it did have a suicide pact with Dagenham …”

(Amended 5th November after David M - see comment below - points out that I forgot the critical element of the joke ...)