Up the Chastity Belt

Up the Chastity Belt also released as Naughty Knights in the USA is a 1971 British film, a spinoff from the TV series Up Pompeii that starred Frankie Howerd and was directed by Bob Kellett.

Eleanor of Aquitaine gave birth to twin sons Lurkalot first and then Richard. But the nobles of the country led by Sir Braggart de Bombast Bill Fraser intercepted Lurkalot, stole him away and abandoned him in a forest to die. He was raised by a family of pigs who belonged to Sir Coward de Custard Graham Crowden who realised he wasnt a pig and took him in as a serf. By way of remittance, Lurkalot aids his master by selling love potions and chastity belts as well as some unusual inventions in the local village as Sir Coward isnt particularly successful a noble. Lurkalot is also visited by strange voices in the middle of the night who speak to him and try to tell him who he really is but get drowned out by events like lightning.All grown up, Richard is bored by ruling England and decides to go on a crusade. Meanwhile, Sir Braggart de Bombast wants to acquire Sir Cowards lands and daughter for himself and makes him an offer. Sir Coward refuses but invites Sir Braggart and his followers to a banquet so as not to offend where a scene is made and Sir Coward refuses to toast Prince John. Offended, Sir Braggart challenges Sir Coward to a duel with Lady Lobelia Anne Aston as the prize. Lurkalot, although not a Knight, takes up the challenge as the Man with no name and defeats Sir Braggarts champion, Sir Grumbell de Grunt David Prowse with the aid of a giant magnet. Realising that the rules of chivalry have not been met, Sir Braggart declares the duel void and declares war. Lurkalot and Lady Lobelia flee the scene to his workshop where to protect his masters daughter, he locks her up with a chastity belt. ........

Source: Wikipedia