Good points Lawrence. And of course we know from Erik that Mr Cox will address them.
In which case Mr C must have found proof of the existence of the limited liability company that Mac claims is the bottler of the various vintage bottlings of Macallan.
Afaik, limited companies in the UK had to be registered under the Joint Stock Companies Act of 1856 and its successor legislation (see http://history.wisc.edu/dunlavy/Corporations/c_laws.htm
for quick guide)
So it will not be difficult to find evidence of the existence of a ltd company at Companies House in London etc.
That is, if it existed as a limited company (which is presumably what it must have been, if it had "ltd" in its title!).
Sorry if this legal malarkey is a bit tedious and confusing (for me too!). It would be simpler and more satisfactory if Mac could just provide a reference from their archives, from the trade press or from official records of the day, to prove the existence of this newly-rediscovered bottler.
Why not post it now, on the Mac website alongside the Vintages offers? Or in the blurb about the relevant bottles and bottlers that already exists at the foot of each page? That would be a simple task, and would put an end to all this speculation and brou-ha-ha.
Latest news of the auction of the 1870 Mac bottle:
"Current Highest Bid: £8900.00"