I must be living with my head in the sand as I had not picked up on the fact that (it is proposed that) Arctic Warbler is no longer to be part of the Phylloscopus 'family'. See this tree http://www.jboyd.net/Taxo/seicercus.pdf
Moved, it is to be treated as Seicercus borealis, with xanthodryas and eximanandus to be 'split from it. Further, this tree suggests that the Green/Greenish/Two-barred Greenish complex is also part of Seicercus, but there are other changes.
Greenish Warbler as such is S. trochiloides, but that viridanus is closer to Green Warbler S. nitidus and called Western Greenish Warbler S. viridanus; obscuratus, treated often as a race of 'Greenish' is closest to Two-barred, but named as Dull-green Warbler S. obscuratus.