Hi! Wondering what font is used on this old poster I found in the shed. I have not seen it used on any other posters on https://railwayposters.co.uk/. Thanks!

Appears to be a metal type version of Gill Sans.

Thanks a lot, Kevin! Yes I thought it could be a variation, as L.N.E.R used Gill Sans for its logo. It has a quite different |a|, |d| and the |S| is less top-heavy - which version of Gill Sans/similar font is closest? Thanks.

I feel this is slightly closer? (I don't think its for sale though)

Also this middle |a| looks familiar. These were ideas that didn't make the final cut of Gill Sans

The use of Gill Sans for LNER posters is well known. No doubt about it. Just google “LNER Gill Sans”. 

Keep in mind that letterpress fonts can have significant design differences in different font sizes, since each size could be an individual drawing and cut (in metal). Since the poster shown is a reproduction, it could also be that differences are the result of retouching done for the reproduction. 

This sample from 1937 includes an a and d that match your sample. If you click through the other samples at the first link I posted (see the far right column / section titled "Info"), I think you'll find an S that is a better match as well.

When older typefaces were digitized, the sources could vary widely—was the digital version based on original metal matrices, a printed type sample, or a later phototypesetting version (if one existed)? And the tastes and prejudices of the era in which the digitization is done can also influence which source was used and which alternate characters make it into the digital version.