This tiny bottle of Black Bottle Scotch Whisky was definitely made some time between 1976 and 1979. Unlike many of the bottles where it’s hard to pinpoint a general time period, let alone such a specific range of years, this one came with some clues.

You know how there’s a saying about the US and the UK: two countries divided by a common language? Jumper, boot, fanny – the landmines are everywhere. Well, it turns out that for over a hundred years we were divided on alcohol numbers, too.

The concept of proof originates in 16th century England, where you would “prove” the alcohol content of a spirit by seeing if gunpowder would still ignite if it had been soaked in it. By that measure, 100 proof worked out to be 57.5% alcohol by volume. And even as the process got more scientific in the 17th century, that percentage stuck. Meanwhile, in America in 1848, proof was defined as twice the alcohol percentage by volume, so 100 proof was 50% alcohol by volume (ABV).

This bottle of Scotch is proudly labeled as 70 proof, which would be an unusually low proof for a whisky. Unless, that is, it was from the UK before 1980, when they switched over to the ABV method mandated by European Union and already in use in the US. Since there’s only proof on the label, and no ABV, it has to be from before 1980.

It also has measurements in two units: 4.7 cL and 1 2/3 fluid ounces. In 1980 the whole world went metric when it came to liquor bottles. But in the transitional period just before then, bottles could have both. So why not before 1976? The label also has an “e” symbol, which is a measurement standard used the European Economic Community that went into effect in 1976.

So what was Black Bottle Scotch Whisky like in 1976-1979? By all reports, probably not great.

As a brand, Black Bottle Scotch started in 1879, a project of an Aberdeen tea blending family by the name Graham. While it was initially packaged in black glass bottles, they were sourcing those from Germany. When World War I broke out they switched to the same green glass as my bottle. From its launch until 1959, one site described it as “one of north-east Scotland’s best-kept whiskey secrets.” As a blended whisky it would have been a mix of both malt and grain whiskies, but a high portion of the blend would have been rich and peaty Aberdeenshire blends.

That all changed in 1959. The post-World War II period was a boom time for Scotch in the United States. The UK had massive war debts to pay off, and by 1954 75% of all Scotch whisky production was being exported. Most of that was flowing into the US, where – thanks to the dual hit of Prohibition and World War II – American whiskey was still pretty terrible. And in 1959, perhaps needing to feed US consumer demand, Schenley Industries Inc bought Gordon Graham & Co Ltd, aka Black Bottle Scotch. This reportedly led to a decline in quality, as the brand became a more standard blended whiskey along the lines of the Dewars, Cutty Sark and J&B labels it would have been competing against.

Black Bottle was sold again in 1990, and this time into a very different Scotch landscape: a little lull between the last boom time and the one still to come. But I know there are at least a few more Scotch bottles in these boxes, so I’ll save that story for a future bottle. In the meantime, if you’d like to taste some for yourself, the brand was re-launched in 2013, supposedly inspired by the original 1879 recipe and once again in a black bottle.

Watch me taste this bottle with Neill Murphy.