Ptarmigan/ Dick,

Tenor vs Tenor-treble

There is no absolute terminology and the meaning of the terms have changed in history.What I have myself are Wheatstone 48key Aeolas from the 1930s when the 48key tenortreble was introduced by Salvation Army as a "new model" meant to be particularly suitable for SA use.(There were flatended ones made also).Those are exacly alike same types with 56 or 64 keys.According to 1935 pricelists a 43key model C-C was offered as well but I haven't seen one.

Now "Tenor".In principle and generally speaking concerning note range you expect a "tenor" to be starting from C a fifth below the low G on
the treble.To make a "tenor-treble" analogous to baritone-trebles it should be sounding exactly the same note when played like a treble and the hand in the same position.(this is not regularly true though)
A common "baritone" will sound one octave lower played like a treble.

The systematic formalist I think expects a proper "tenor" analogously to be transposing a fifth down and transpose to the key of F - not sound in the key of C

This is practised with basses! The proper "doublebass" concertina transposes 2 octaves down and mostly runs down to the G two octaves below treble G as well.And the smaller bass which usually runs down to the C one octave below tenor C IS usually transposing a fifth down and consequently an F-instrument.
(To make confusion complete those basses often are called Bb-bass and Eb-bass respectively since in concertina bands they were used to play the brass band music for Bb and Eb parts respectively)

Steve Dickinson (Wheatstone Co) has adopted this terminology and does make 48 key tenor-trebles like the SA model AND a a transposing 48 key "tenor in F" as well.

When reading old litterature and pricelists (before the extended range instruments,tenor-trebles and baritone-trebles, were introduced) you may find them speaking of "tenors" (in early days single action models) but the actual 'tuning' may not be specified.You may also find that what we now call a "treble" may have been called a "soprano"

Goran Rahm