For the sake of convenience and consistency, all the beers were brewed over-strength and then liquored back - watered down in plain English - to get to get to the right ABV. Dann hated it because he said it adversely affected the beers.
So I was quite surprised to see someone advocating the practice more than 100 years ago.
"Blending of Strong to Weak Beers.
In many cases the weak beer of an English brewer — a beer of say 17 lbs. gravity — is a very inferior kind of fluid, thin, washy, and of no stability; this character arising, in many instances, from the practice of diluting the stronger worts with very inferior weak runnings from mash tuns. The limitation of sparging lengths is, of course, a good plan, as also the method of "boiling off" worts in single lengths, but a perfectly successful method is to ferment no wort, from which pitching yeast has to be cropped, under a gravity of 21 or 22 lbs, but to attain the desired original gravity towards the latter stages of fermentation by blending down with liquor, properly boiled, coloured, and cooled. It is necessary, we presume, to obtain "a permit" from Excise authorities before attempting to carry out the suggestion."
Holmes' Brewing Trade Gazette - Saturday 01 October 1881, page 13.
No-one today would consider a beer of 17 lbs gravity (1047.26º) a weak beer. But British beer was much stronger back in the 19th century.
A typical brew would have worts both much stronger and weaker than 17 lbs. These would be blended up (possibly making more than one strength of blend) after boiling but prior to fermentation. Loking at a random brew (Barclay Perkins X Ale from 1880) it had three worts of 33.4, 19.2 and 11.5 lbs (1092.85º, 1053.38º and 1031.97º) to make a beer of 21.8 lbs (1060.6º).
Only wanting to pitch yeast that had been produced by the fermentation of a wort of at least 1050º caused all sorts of problems when beer strengths were slashed during WW I. And led to brewers doing excatly what was suggested here: brewing to a higher strength and then watering the beer down post fermentation.
This wasn't usually allowed under the Free Mash Tun Act. Not sure why. You could add water to a wort before fermentation but not after it. Which is why there's mention of getting a permiy from the Excise.