Thanks for your prompt reply. First, the dating of the bottle:-
Earliest Date-- D.C.L. bought Haig & Haig from Robertson & Baxter in 1923 and transferred its assets to John Haig in 1925. So 1925 is earliest date.
Latest Date-- My mother worked in John Haig's bottling hall until she married in 1931. (I was born in 1932). She "liberated" this bottle before she left her employment.
Marks on bottom of bottle:- None (see photograph). This in itself is strange as most mass-produced bottles will have some form of reference on them to facilitate reproduction.
This and the lack of information from other people that I have contacted lead me to an outlandish but plausible theory:-
The bottle was never on the market!! It was a "make-up" for appraisal for a proposed bottling that never took place. A short run of bottles could have been made in any of the glass bottle works owned by the D.C.L. The labelling is easy enough to do and could account for the out of date analysis which refers to John Haig whisky in general and not to this particular bottle. The carton that accompanies the bottle is of poor quality cardboard and I don't think it would be used for the final retail product.
My mother did not drink and I think she may have taken this bottle more for bravado than for the whisky. I just wish that I had discussed it in more detail when she was alive but at that time it was just a bottle in a cupboard and not of much interest.
Any thoughts on the above??