The bonus production from having a lot of steam mill is the same for every empire, except England does not need coal to achieve it
Honestly, due to not needing coal, and if i remember correctly, you can get Steam Mills tech tier earlier, their power spike was crazy.
The main reason im always play Autocracy is to have 100% more resources to get crazy amount of prouction, this England ability alone,
considering there are really two buildings that require coal, means, their need for coal is 50% of every other civilisation, so indirectly you can say
that they have 100% more coal, with additional bonus, that they do not actually need to mine it. In my opinion this is OP.
That being said, lastest rework of coal. can let you fight for coal an era earlier now, so you have time to prepare, and you kinda know like
100 turns earlier, if your power spike will be big or not, so that kinda mitigate England power spike, which biggest advantage relied on the fact, that
they will have Factories regardles of coal availability.
This also is very synergistic with England, since it allows them to focus on their main strength which is spying by adapting Order, having at the same time
crazy amoun of production. But at the same time, i think its kinda sad, that you are basically kinda forced to get into Order, since you dont have need
to get into Autocracy. Id like actualy to see some features, that would give england a meaningful reason to chose non-Order ideology..
Since Factories do require coal for work, i would say, much better design would be to give 1 coal every 2 factories. That would force England, to have actually
some coal, to get their coal oriented trait going. And that would actualy mean 50% more efficiency in managing coal, which is still a lot.