sfaiaa polydor's licence to the uk rights to releases from kama sutra (& the allied buddah) commenced at the beginning of 1970°, so this compilation must have been released in the uk in january 1970 at the earliest, the original merkin publication dates (actually 1966-8) of the recordings on the label & lp sleeve back cover interview of 1968 notwithstanding.
there was no "songbook volume 2"; this lp was issued to capitalise on john sebastian's recordings as a leading light of the lovin' spoonful after the successful launch of his solo career - after leaving the spoonful, and with another record company.
° - evidently, it has transpired, leaving the uk rights to some or all of the catalogue released in the uk (& sub-licences thereof) by pye records with them (& their successor record & music corpses)