The London & North Western Railway (LNWR) made absolutely everything itself, from its steel rails to its steam locos, from wheelbarrows to artificial legs. Even the bricks for its buildings. So yes, they made uniforms as well.
According to a 1903 map in Brian Reed's book, "Crewe Locomotive Works and Its Men" (page 123), the "railway clothing factory" was on the west side of that part of Bridle Road running roughly north/south. (Do a Google Street View and you'll see a saw-tooth roof building fitted with north facing roof-lights. I'm guessing that's it since it doesn't look like a later replacement. In fact it looks like an smaller version of an LNWR loco shed!)
Your chair caster would have cast chairs for the railway track. These are screwed and spiked to the wooden sleepers, and are sort of U-shaped in cross-section on a bigger base. The rails dropped down into the "U" and wooden wedges are hammered home on one side between the rail and the outer jaw of the "U". The inner jaw has a curl over at the top of the "U" to hold the rail in place. Go and look at Wikipedia
http://en.wikipedia.org/wiki/Rail_fastening_system and find the series of photos at the bottom for Rail fastening types - photos "Track joint and chairs" and "Steel spring keyed rail in chair" will show you the chairs that he spent his days casting.
