This is my 2nd go at a Vintage key copy, I chose this time a Partrick & Carter key, original pics below right which were kindly sent by Tom Perera from his website, the fancy bridge over the arm caught my attention and the cut and shaped brass base, both of which were tricky to make with my limited tooling,  the bridge or arch is made of  five parts sweated and bolted together to get that swept shape, also the arm has some fancy tooling,
there are differences, the shape of the base is slightly different not so cut in as the original, and there is a disk shape that the gap adjuster works against , the arch maybe slightly higher but hard to tell from the only pictures I have, It has a nice action unlike a real Railway brass pounder, a little tricky to set up perhaps but hey this is a real vintage design :()
You can see from these pictures how they got the name keys!! it does look like some mad door lock and key hi!!