Clear as mud

So the BBC's got a "Normans" season on at the moment. They were trailing it on Radio 4 the other day, ad I was most baffled until something right at the end of the trailer/spot made me twig:
"Ooh! 'Normans' as in Battle of Hastings. Not 'Normans' as in 'people called Norman'."
*husband nearly falls off chair laughing*
"Well I did think it was a bit of an odd theme to base a season of programmes on..."