I'll start with a few words of explanation about how I've selected that data. London brewers made a variety of Porters in this period. Most of which had no equivalent at William Younger. Keeping Porter, Export Porter, Export India, Bottling Keeping. As beers that were meant to last a long time before consumption, they were naturally more heavily hopped than standard running Porter. Younger's BS wasn't aged and it wasn't brewed for export. Comparing it with Export or Keeping Porter would be like comparing apples and persimmons. Consequently, I've only included London Running Porters.
I can see a similar to phenomenon to that in action with Pale Ale. Porter being an alien style, Younger appear to have copied London brewing practice. There are several points of dissimilarity with the other beers in their range: pitching temperature, length of boil and attenuation all jump right out.
Here's the table:
|England vs Scotland early 1850's Porter|
|Date||Year||Brewer||Beer||OG||FG||ABV||App. Attenuation||lbs hops/ qtr||hops lb/brl||boil time (hours)||boil time (hours)||boil time (hours)||boil time (hours)||Pitch temp||max. fer-ment-ation temp||length of fer-ment-ation (days)|
|3rd Nov||1851||Younger, Wm.||BS||1056||1015||5.42||73.21%||23.87||2.86||2.25||63||72||5|
|11th Oct||1851||Younger, Wm.||BS||1057||1017||5.29||70.18%||21.75||3.08||2.25||64||73||5|
|28th Feb||1852||Younger, Wm.||BS||1057||1018||5.16||68.42%||23.87||2.93||2.25||64||72||6|
|15th Nov||1851||Younger, Wm.||BS||1060||1022||5.03||63.33%||23.46||2.61||2.25||63||72||5|
|22nd Nov||1851||Younger, Wm.||BS||1060||1021||5.16||65.00%||25.26||2.93||2.5||64||73||5|
|29th Nov||1851||Younger, Wm.||BS||1060||1024||4.76||60.00%||27.37||3.17||2.25||64||71||5|
|William Younger brewing records document numbers WY/6/1/2/3 and WY/6/1/2/5 held at the Scottish Brewing Archive|
|Whitbread brewing records document numbers LMA/4453/D/09/043, LMA/4453/D/09/044, LMA/4453/D/09/045, LMA/4453/D/09/046, LMA/4453/D/09/047 and LMA/4453/D/09/048 held at the London Metropolitan Archives|
|Truman brewing record document number B/THB/C/052 held at the London Metropolitan Archives|
Let's start pulling apart the stitching with hopping rates. It doesn't take an expert to see that there's bugger all difference in the hopping rate per barrel. All the beers, English and Scottish, have about 3 lbs per barrel. In the early 1850's Younger's Porter was hopped at the same rate as equivalent London beers.
Boiling times are more tricky. Because of the different number of worts. London Porters were blended from 3 or 4 worts, which were all boiled for different lengths of time, getting longer as the wort got weaker. Younger's Porter had a single wort. A direct comparison isn't possible. What is clear is that Younger boiled their Porter for much longer than their Ales. About twice as long, to be precise. It looks like they are trying to imitate the long boils of London brewers. What can I say? In the early 1850's Younger's Porter had a longer boil of the first wort than equivalent London beers.
Thankfully, pitching temperatures are dead easy. Almost every beer, English or Scottish, was pitched at 63º or 64º F. I can see no difference. Unfortunately, I don't have the maximum fermentation temperatures for any of the London Porters. But the pitching temperature and max. temperature of Younger's Porters are considerably higher than of their Ales. The pitching temperatures are a good 6º to 8º F warmer. As the temperature didn't rise as much during fermentation, the difference in the maximum temperature is smaller, 4º to 5º F warmer. It again looks as Younger deliberately copied London practice. In the early 1850's Younger's Porter was pitched at the same temperature as equivalent London beers.
Younger's Porter was a the low end of gravity range covered by the London beers. The average OG was a full 4 points lower. Though the average FG was a touch higher. Surprisingly that's not really reflected in the attenuation, which is only a little lower. There's not much that can be said, except: in the early 1850's Younger's Porter had about the same level of attenuation as equivalent London beers.
I think the results are very clear: Younger's Porter was very similar to the Porters brewed in London. There was one enormous difference. The amount brewed per batch. Younger's brew length was just 40-odd barrels. The London ones between 600 and 1,000 barrels.