Yeah it was a worldwide network back then, if you managed to get a tape no-one else had you could get fantastic trades, I remember someone giving me his own recording of Bowie as Ziggy at the Top Rank in Hanley 1973, I got about £500 worth of vinyl trades for a cassette, I also used to have a mate who would copy things from the BBC vaults, most have now been reshown but I had a lot of TOTP which still hasn't been rebroadcast - I lent those out and never got them back.