Wonderful how a conversation (even one on the net by posting on this forum) can give clarity. deefstes caused me to look wider than just Buffy and Long-billed Pipits to include the plain-backed Pipit. In so doing I learned a bit more about the ID features of pipits while deeply delving into Faansie Peacock's PIPITS of Southern Africa. (Roberts VII does little to help in separating these difficult critters)
The table above reflects only some (not all) of the ID features one can look for. Some of the best ones, like behaviour and song, I have no record of and therefor this difficult slog is the result.
The "base-of-the-lower-mandible" bandwagon was the first thumbs-down for Plain-backed Pipit. However, two other features, tail length and the hind claw comprehensively put PBP into touch. So, back to my original two...
My table should have included another row "Colour of underparts". Apart for having distinct to poorly streaked upper parts, the Long-billed Pipit's underparts are generally much darker than that of the two other birds under consideration. In any case, LBP's breast markings is a feature not seen in the subject bird.
Once I got to this point where I was just looking for further confirmation that BP was my bird, the thumbs-ups just kept on flowing!
The Buffy Pipit is one of the largest of the 'Large pipits' group
with a particularly long tail and a long neck.
In the field, the head usually appears rather small in proportion to the body and the crown is flattened .
In Buffy Pipits, the face is usually quite plain,
with at most a paler supercilium and sometimes a faint malar stripe.
They lack the well-defined and bold facial markings of the smaller 'Large pipits'.
Their stance often shows outwardly splayed at the knees.
The hind claw is thick and short.
Buffy Pipits are mostly associated with open savanna habitats, particularly in overgrazed, agricultural or recently burned areas.
Buffy Pipit exhibit important behavioural characters that help with their identification. In particular, the tail wagging is very extreme, involving the whole rear half of the body with the tail extending upwards so far that the vent can easily be seen if the bird is viewed from behind. Also, Buffy Pipits tend to wag their tails more frequently and more continuously than the similar Plain-backed. This is where my powers of observation failed me. I do NOT remember having seen this individual do the tail-wagging bit.
However, based on the other factors I am now 95% convinced that the subject bird is a Buffy Pipit.
I will appreciate comments very much