I'd better apologise too then, since 'plonker' and 'pillock' are both euphamisms for profanities, ( guess what!), but manufactured ones created by 'Aunty BBC' to avoid offence. Plonker comes from Only Foools and Horses, and Pillock comes from Steptoe and Son.
Reminds me of Winston Churchill, who added "Spherical Objects!!!" on the bottom of a memo he returned to sender. The memo came back with-
"Who is Spherical, and what does he object to?"

Alan


Wood work but can't!