Actually, Terry T, my concern about drought is what led me to the possible benefits of mycorrhizal inoculation to bolster any natural inoculation - or lack of. (Rain-water capture for irrigation is all very well, but only if there is enough intermittent rain to capture - at the moment my irrigation is all off the mains!)
But I'm somewhat bemused by "your" scientist's view on this (although I appreciate the point about crop or variety specifics): apparently the vast majority of plants have formed some sort of natural association with "beneficial" fungi over millenia in all habitats across the globe so, leaving aside whether mycorrhizal supplements are worth considering or not, the association obviously works for both plants and non-destructive fungi in more ways than one; not just with regards to finding/exploiting scarce ground water. [Edit: Assuming UK produced mycorrhiza (mycorrhizae ?) is applied to common indigenous plants, surely there must be a chance that a good bond will ensue !?]
However and whatever, the "drought tolerance" comment was music to my ears!
[I'm interested in both endo & ecto mycorrhizal supplements presently - me thinks I would be looking at endo for apples (not sure) and ecto for willow/conifers - althought willow seemingly forms both endo/ecto associations]