I saw one record listed on a gumtree-type site with very little info about it. I started messaging the guy back and forth and it turned out that he had a collection of them, all from Tony Hall's estate. He sent a letter of proof over as well as some general info (which was nice as it wasn't like he had overpriced them to begin with). After chatting a bit more he offered me a price for a set that I was interested in, we haggled and came to an agreement. Really easy process to be honest and I believe I was the first person to have had a look at the collection, so I managed to get a lot of the gems.