Until the middle of the 20th century there were restrictions on the use of many words and expressions on stage and in published books. Many alternatives were used to circumvent the censor. Even Brendan Behan's novel "Borstal Boy" uses "Fugh" and "Fughing" and when Dorothy Parker was intoduced to Behan, she is reported to have said "Oh you're that young Irishman who can't spell fuck ! The prohibition also covered the various names of the Holy Trinity - hence terms like "egad".

When you consider that the swear words allowed in books and plays barely a century ago would have been much tamer than those really in use amongst unpolite society, how much can we rely on those recorded in even earlie tims ?