Since I had a pickle/chutney/hot sauce/jam/preserves company at some stage in the past, the historical part of "conserves"is fascinating to me.
Pickles originated in the UK in the 14th century, approximately, and were basically the same as their Dutch/German counterparts: vegetables (especially cucumbers, onions, and cabbage) preserved in brine and/or a vinegar solution. In the 18th century, chutney arrived in Britain from India; probably the most famous is the mythical Major Grey's mango chutney, and what we call piccalilli (and others call chow chow), based on a Bengali pickle.
Where the idea of Branston pickle came from, somewhere out of the blue in 1922, I've got no idea. Why it was called a pickle, instead of a chutney, again, no idea. Perhaps the creator had had too many gins, or decided that the vinegar content merited a "pickle" title - again, no idea. What obviously came on the scene was an absolutely delicious condiment which is now available in more than 50 countries.
Ploughman's, or Farmhouse pickle probably didn't arrive on the scene until the 1960s, and my theory is that is was designed to accompany a traditional ploughman's lunch. The aforementioned "lunch" (and I ate it many, many times ) was basically a chunk of crusty bread and a chunk of Cheddar cheese, occasionally accompanied by a pickled onion ( or slices of raw onion) or a dollop of Branston pickle. Ploughman's pickle was evidently an attempt to compete with Branston's, and history will tell that they failed miserably; Branston is unique.