There are a few explanations for this phrase. Mostly stem from a mythological ship builder or ship building company based on Merseyside during the 19th century. The most probably origin comes from the term ‘jury’ which meant temporary or makeshift as in ‘jury-mast’. A Jury mast was constructed as a means to getting back to port when a ships mast was damaged. Maybe it was down to the French this time mispronouncing and English phrase!