I think Babo 91 is correct in saying the first solo (as well as the second) is by Dave. If you listen to live recordings from after H joined the band, H would do the first solo, yes, and Dave the second only. But listen to some versions of that solo, and you will hear that on many nights the second solo (Dave) sounds very much the same as the first solo does in the studio. The playing style, tone etc is also very Davey-like. I'm almost certain that Dave plays both solos on Strange World (both on The Soundhouse Tapes, obviously, but also on the debut album).