If you are hoping for a serious discussion on the matter Dick I surely am "in" and quite interested in the questions but I fear there are few definite answers.The documented scientific acoustic research on these matters is poor and occaisional.There does exist quite good studies on accordions and of course the results should be compatible concerning concertinas but to be absolutely shure of course some of the experiments should be carried out likewise with concertinas but this has not been done yet.I make some short replies to your issues:

1) is it the steel used for the reeds or the wood that is used in the construction.

RE:Not the "steel" per se but the qualities of *reed* is usually the most discriminating factor for the sound of free-reed instruments

2) what evidence is there that steel produces different sound from concertina to concertina?

RE: Again, the *reed* definitely, yes. The reed material definitely, yes. (differences between brass, steel and alloys)
There hs been much talk and marketing gimmicks in history regarding "hard steel" and qualities thereof. Thee truth seems to be that the spring steel used by different makers has been basically the same with very small differences. I have for instance checked with some prominent swedish steel works which have delivered "musical steel" for a century to Italy and Britain and the specifactions have not been changed at all.

3)there is evidence that choice of wood used in the construction affects sound.

RE:Very questionable. There always are other co-existing variables that may effect tone to some part as well and no really satisfactory comparisons have been made. The lab tests with accordions reveal that box materials ( like reed pans and covers) generally have *very* little effect on sound

4) there is also evidence that brass reeds sound different to steel

RE:In practise mostly yes but some makers definitely claim that it is quite possible to process a steel reed to make it sound like a brass reed. The characters regarding sound onset, amplitude/pressure relation etc might differ too

5) and that wooden ends sound different to metal ends.

RE: Not necessarily so! but co-existing differenes make "metalended" instruments mostly sounding different that "woodenended" ones.Experiments with accordions show very little or no difference but possibly the smaller measures related to concertinas may cause different conditions. A matter to investigate...

6) how important is wheatstone radial construction compared to jeffries and crabb construction?

RE: In principle there should hardly be any importance for sound but theoretically one may speculate that minor resonance conditions might influence the tone.The sice and height of the chambers have particular influences however:

7) how important is the tapered reed chambers used on wheastone concertinas.

RE: The motive for them is to allow full reed travel when vibrating.
The height of the chamber should be minimized to reduce onset time.
So - the motive for the tapering is *not* to influence the tone. Maybe it has some effect un-intentionally all the same.My own impression is that for otherwise twin-like Wheatstone trebles which I have compared the non tapered instruments might sound a bit "thinner" in the lower octave.