Tried to post this yesterday, and there was some kind of Javascript problem...
25 Hz like DC? Er, sort of, but not that much. I believe the main motivation behind 25 Hz was that, back in the early days, it was hard to build high-RPM motors that wouldn't self-destruct. A four-pole synchronous motor running on 25 Hz would run in the range of 700-750 RPM, which was reasonable for large industrial motors and machinery in the early 20th century. At 60 Hz, it would be around 1700 RPM, which was too fast.
Related to that, I think the Birmingham steel mills wanted 25 Hz mainly for rolling mill machines. The rolling and extruding machines rolled and extruded steel slabs into sheet, bar stock, tubing, etc. I doubt that they wanted it specifically for induction for the simple reason that, up until near the end, the Birmingham mills didn't use any induction furnaces. It was all open hearth, baby! (And seldom was a more effective way of polluting a city's air ever devised...)
There's a museum in Birmingham now called the Sloss Furnaces. Sloss was a pig iron plant, with blast furnaces; all they did was make make pigs which were sold to the steel mills. For most of Sloss's existence, it actually used a decentralized system for electricity. Most of the big machinery, such as the blast furnace's air blowers, were powered by steam. They burned the blast furnace exhaust gas in big boilers to produce the steam. (Most of the exhaust from a blast furnace is carbon monoxide, which actually burns rather well.) The steam was distributed all over the facility. Any place they needed electricity, for lights or small machines or whatever, they tapped into a steam line and hooked up a steam turbine connected to a small dynamo.