David,
Thank you so much for your advice.
As you describe, the UK is still dominated by hand work, and very pretty it is too, but most guns from 2nd and 3rd tier makers just can't justify the expense however well justified. I will certainly contact Darcy Echolls about this job.
I take your point about no damage being unrepairable but sadly, the remaining head of the stock is very badly carbonised from a century or more of over oiling (the bane of all restorers) plus someone cut out the break to re-use some of the lovely old walnut so I am missing a 5" section!
Thanks again.