I know what you are saying Kev there is often a bit of confusion over what constitutes the upper, middle and lower on a river which is 220 miles long.
I have always considered Worcester to be the start of the lower or the end of the middle with Diglis weir being the natural demarcation, I am aware however that others would say the lower river is the tidal region below Tewksbury but to me that is the tidal.
I have heard the stretch between Stourport and Worcester being described as the upper lower but to me it will always be the lower middle, the middle being defined as the river between Shrewsbury weir and Diglis though some would say it extends up as far as the confluence with the Vernwy at Melverly.
That would actually make more sense geographically and in a fishery sense as the river character does definitely change above that point and the fish species go from being predominately coarse below the confluence to predominantly game above, though the chub fishing between Newtown and Welshpool can be as good as anywhere in the country.
That of course would make the bit between Melverly and Shrewsbury the the lower upper or the upper middle and the upper going from Melverly to the source, though in a fishing sense it is fairly barren on the mountain above Llanidloes.