@mitchagain - yeah, I'd just looked at the same Wiki article that you did! 😀 I didn't know that John Bonham was on that session - I like learning things like that! From reading the article, I got the impression that it was Parker, not Holdsworth. In fact, I just looked at the Allen Holdsworth Wiki, and it says:
There has been an urban myth, propagated in part by the singer Donovan, that Holdsworth played the fuzztone solo on Donovan's 1968 hit "Hurdy Gurdy Man", but the solo was actually played by Alan Parker.[22][23]