I was wondering the same and got curious enough for a quick search. Saw someone recommending Branston Pickle and it looks similar
Branston Pickle is made from a variety of diced vegetables, including swede, carrots, onions and cauliflower pickled in a sauce made from vinegar, tomato, apple and spices.[9] While not a chutney, Branston Pickle is sweet and spicy with a "chutney-like" consistency, containing chunks of vegetables in a thick brown sticky sauce.[9]
Aha! I appreciate the explanation! I've never heard of such a thing and in the US our pickles are green. Brown pickles would be something well past the point of being safe to eat over here :)
Yup, branston pickle is a unique and potent thing. Well worth at least trying.
It's a relish though, not a whole pickle that you chop up yourself.
No joke, if you can find it locally, try it. Amazon carries it here in the US, but you'd be using Amazon, and I'm not sure how you feel about that. It's a strong, intense flavor. Like has been said in other comments, it's best experienced with cheese, on bread.