When I asked Roy himself, he confirmed that the first organ he owned was a Lowrey Heritage, which he used on The Peddlers' early recordings, but in 1967, Manfred Mann switched him on to the Hammond organ, and from the album "Freewheelers" (1967) onwards, he used a Hammond A100, which he had extensively customized including a wah pedal. For the live performance in the first video (1971)
, he played a Lowrey Berkshire that was provided by the TV studio, but in the studio version on the album "Three For All" (1970)
, he played the Hammond (you can hear the Hammond's percussion and chorus vibrato in his solo at 1:39-1:54).