Check out Mastermix.org. It:
focuses on the mid-1980s London soul radio stations which introduced the mastermix genre to the UK. The sounds on this site are predominantly taken from FM pirate broadcasts, recorded to cassette. Often the recordings suffer from interference, drop outs, print-through and occasional ‘record button’ accidents. But generally they have a warm, authentic quality to them.
There are dozens of mixes for listening or download. I spent the mid-80s in Canada, not London, but the nostalgia is still there. They’ve even got recordings of radio jingles and adverts from the era. Fun.