Hi again, thanks for the replies, all of which have been helpful in some way so far.

It is now evident to me that flute is impossible as it doesn't go down low enough.

I had questioned fiddle, as there are Secundo parts to this MS which utilise the normal fiddle range, from below middle C up to (in abc), whereas the is absent from this Primo instrument.

The notes above are such as to require, in these tunes, a shift of position rather than a thrown pinkie. This is an ability from classical technique which is otherwise under-utilised in the MS, but it is not impossible for it to be fiddle with a bit of extended technique, and that might be the conclusion.

The compass seems, from the Dolmetsch site, to be similar to the trumpet or cornet, though the actual notes don't quite match.

The Oboe doesn't go down far enough, but the clarinet seems to be capable of going both much higher and much lower.

BTW, all the parts are in the same key, so there is no transposing going on.