Hi, Welcome to JustAnswer! My name is XXXXX XXXXX X will endeavor to answer your question.
I have been running a worldwide Craigslist search and eBay search every day since you first posted the question.
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Here is the name and contact # XXXXX Mr XXXXX XXXXX On 07939 928551
He was one of the guys who made the speakers at Brinkman. It might be possible that he would knw where there is a pair for sale...?
Also here is a number for a guy in London who had a pair for sale over a year ago.