Scotland was a strange place, beer-wise. Quite different from England. Not so much in the beers themselves as the names under which they were sold. Rather than Bitter and Best Bitter, in Scotland they used shillings to differentiate between Pale Ales of different strengths. With 60/- being ordinary Bitter, 70/- Best Bitter and 80/- Strong Bitter. All very logical. Except when you get to 90/-. Logic would dictate that this would be stronger than 80/-. It wasn't. For some reason 90/- was used for bottled Pale Ales around the strength of draught 60/-. Make any sense to you? It doesn't to me.
The analyses below all come from brewery sources. Pretty much every beer was specifically called Pale Ale (or PA) in the original documents. Not Light, Heavy or Export. Because, despite what later style fetishists might claim, Scottish brewers themselves considered all these beers Pale Ales. Light, Heavy and Export were the names used by drinkers. Much in the same way English beers were called Pale Ale in the brewery and Bitter in the pub.
I'm not surprised the shilling designations have caused so much confusion. Because they don't really pin down a style of beer. Before WW II, 60/- was the equivalent of ordinary Bitter. The sixty bobs I can recall from the 1970's were all Dark Milds. I'll repeat this once again: all the shillings tell you is the relative strength of the beer. Not which style it's in. If you forget this, Scottish beers won't make the slightest sense.
Most of the beers in the table are 60/- PAs. Though not all were clearly identified as that. Their average OG is 1039.4, average FG 1009.6, average ABV 3.8%, average apparent attenuation 75.6%. Retailing for 7d a pint. The William Younger beers from 1921, though not all are identified as such, in the source, are 60/-, 70/- and 80/- PA. Retailing for, respectively, 7d, 8d and 9d per pint. 70/- having a gravity around 1046 and 80/- 1052. This is very similar to the beers brewed in London, where Pale Ales over 1050 cost 9d a pint and ones in the mid 1040's were 8d a pint.
How, in a time when beer strengths weren't public knowledge, did brewers manage to keep their beers of such similar strength? The answer lies in the sources of this information: various breweries' Gravity Books. Brewers kept a close eye on what their competitors were up to. Gravities naturally tended to align with each other.
A final point: colour. That's where there is a difference. English Pale Ales were in the range 20 to 28. I've a log of Whitbread PA where the colour is 34 and there's a note saying "Too high". Most of the Scottish examples are darker, in the 30's or 40's. Or the colour of an amber Mild like Barclay Perkins'. Two of McEwan's Pale Ales from 1924, presumably 60/- PA, seem to confirm the Scottish practice of colouring a beer differently for different markets. Their gravities are about the same, but one has a colour of 35, the other 52. It's unlikely that this could be explained by them coming from different batches or by accident. The difference is too great.
Here's the luvverly table:
|Scottish Pale Ale 1920 - 1924|
|1920||Usher||PA 54/-||Pale Ale||pint||draught||1010.5||1034||3.04||69.12%|
|1920||Usher||PA 60/-||Pale Ale||pint||draught||1012.9||1040||3.51||67.75%|
|1920||Usher||PA 90/-||Pale Ale||pint||draught||1016||1054||4.93||70.37%|
|1921||Bernard||PA 60/-||Pale Ale||pint||draught||1011||1039.2||3.65||71.94%|
|1921||McEwan||PA 60/-||Pale Ale||pint||draught||1007.1||1040.2||4.31||82.34%|
|1921||Younger, Wm. & Co||PA||Pale Ale||9d||pint||draught||1013.1||1053.2||5.21||75.38%|
|1921||Younger, Wm. & Co||PA||Pale Ale||8d||pint||draught||1012||1046||4.41||73.91%|
|1921||Younger, Wm. & Co||PA 60/-||Pale Ale||pint||draught||1011.2||1039.5||3.67||71.65%|
|1922||Ballingall||PA 60/-||Pale Ale||pint||draught||1012.8||1040||3.52||68.00%|
|1922||Bernard||Pale Ale||Pale Ale||7d||pint||draught||1009.6||1039.2||40||3.84||75.49%|
|1922||Bernard||Pale Ale||Pale Ale||pint||bottled||1005.4||1042.5||27||4.85||87.31%|
|1922||Deucher, James Ltd||Lochside Beer||Pale Ale||7d||pint||draught||1011||1039.5||3.69||72.15%|
|1922||McEwan||Pale Ale||Pale Ale||pint||draught||1007.6||1039.8||30||4.18||80.83%|
|1922||McEwan||Pale Ale||Pale Ale||7d||pint||draught||1010||1038.7||35||3.72||74.16%|
|1922||Steel Coulson||PA||Pale Ale||pint||draught||1012||1040||3.63||70.00%|
|1923||Bernard||Carbonated Beer||Pale Ale||4d||half pint||bottled||1012.4||1037.6||45||3.26||67.02%|
|1923||McEwan||Pale Ale||Pale Ale||pint||bottled||1007||1040||4.29||82.50%|
|1923||Murray||Carbonated Beer||Pale Ale||4d||half pint||bottled||1011.8||1035.2||27||3.03||66.48%|
|1923||Tennent||Carbonated Beer||Pale Ale||4d||half pint||bottled||1007||1038||44||4.03||81.58%|
|1923||Tennent||Carbonated Beer||Pale Ale||4d||half pint||bottled||1005.5||1039.6||45||4.44||86.04%|
|1923||Tennent||PA 90/-||Pale Ale||pint||bottled||1006||1039||4.30||84.62%|
|1923||Younger, Geo.||carbonated||Pale Ale||pint||bottled||1007.3||1033.8||33||3.44||78.47%|
|1923||Younger, Geo.||No. 1 Pale Ale||Pale Ale||pint||bottled||1008.2||1014.9||31||0.87||45.27%|
|1924||Bernard||Pale Ale||Pale Ale||4d||half pint||bottled||1013.2||1040.2||35||3.49||67.16%|
|1924||Gordon & Blair Ltd||Pale Ale||Pale Ale||pint||draught||1038.1|
|1924||J. Deuchar||Pale Ale||Pale Ale||pint||bottled||1005.3||1038.9||35||4.37||86.29%|
|1924||McEwan||Pale Ale||Pale Ale||pint||bottled||1008.6||1039.5||35||4.01||78.23%|
|1924||McEwan||Pale Ale||Pale Ale||6d||pint||1009.4||1038.7||52||3.80||75.71%|
|1924||McEwan||Pale Ale||Pale Ale||pint||draught||1041.6|
|1924||Murray||Pale Ale||Pale Ale||4d||half pint||bottled||1011.1||1036.3||25||3.26||69.42%|
|1924||Murray||Pale Ale||Pale Ale||pint||draught||1037.2|
|1924||Murray||Strong PA||Pale Ale||pint||bottled||1013||1057||5.73||77.19%|
|1924||Tennent||Pale Ale||Pale Ale||4d||half pint||bottled||1009.8||1037.3||48||3.57||73.73%|
|1924||Younger, Geo.||Alloa Pale Ale||Pale Ale||bottled||1039.7|
|1924||Younger, Wm. & Co||Sparkling Ale 90/-||Pale Ale||pint||bottled||1010.5||1041.5||30||4.02||74.70%|
|Thomas Usher Gravity Book document TU/6/11 held at the Scottish Brewing Archive|
|Whitbread Gravity Book document LMA/4453/D/02/001 held at the London Metropolitan Archives|
|Younger, Wm. & Co Gravity Book document WY/6/1/1/19 held at the Scottish Brewing Archive|