Here's some info that might put you at ease on this bottle a bit....
First off, the term "The Very Finest Scotch Whisky of Great Age" was first used after the end of WWII, as government demand for wartime alcohol was easing up on distillers and the general aging of whisky reverted back to the pre-War standards. (Oldest dated reference to this usage, is on UK-market bottles made after 1946-1947....North American-market bottles used the term "Blended Scotch Whisky".)
The "11" marking on your bottle is simply a reference as to the which machine produced the bottle...this is done to ensure quality of production, and quick identification & correction of any machine producing inferior bottles.
I will agree with blenderm on the fact that the "NB" marking was no longer in use by 1930...so that part is a bit unusual to find on your label.
As for the foil-wrapping rather than a lead-wrapping, this is not a big surprise to find in a 'customized' bottling dating to just after WWII...Most distillers had discontinued the lead wrapping by 1943, as lead had been in high demand for the war effort, and was also banned from export by France (a major supplier).
From the point of a restaurant seeking a customized bottling, there is no reason to expect that they would not require a 'wrapping' to differance their bottling as something 'special' during a time when people had recently gotten used to going without...the wrap gives us a certain level of 'assurance' to the contents, and this would be a prominent point in producing a special bottling for higher end customers. Being that lead was still at higher prices, they may have settled for tin-foil as a cost effective alternative that still allowed them to provide the 'assurance' of a wrapping.
The same holds true for the point of the driven cork - Many brands of current wines are sealed with screw-caps, but the same wines are also 'custom bottled' for establishments with tradional cork closures upon request, as this provides a sense of ambiance to the end buyer who may not look kindly on a 'house wine' with a screw-cap.
Personally, I think you probably have a nice late-40's to early-50's bottle ! It would be good to check with the manufacturer on it anyways...there is still the item of the "NB" marking to clariffy, and they also might be able to add detail to the dating of this bottling as well.
Walter C Hurst