Yes the running in boards did have the Saffron Walden name on them but these were removed in 1964 when the branch closed. I think they are now at the miniature railway, The reference to Saffron Walden was not reinstated until 2012.Those signs hark back to the days of the GER's Saffron Walden Railway, for which Audley End and Bartlow were the termini. It was a railway of which my mother has vivid memories from her childhood and it closed in 1964.
As far as my own research has concluded, I believe the Audley End Minature Railway now runs somewhat in its footprint and indeed traverses a small GER bridge (I believe over the River Fulfen) in the grounds of the house, adorned with at least one plaque stating its provenance.
A look at the current OS map will show that the Audley End Miniature Railway is, at its closest, 0.4 mile from the old alignment of the Saffron Walden Branch. In fact the building of the miniature railway started before the branch line closed. The bridge in your picture is part of the original estate as the railway followed existing tracks when it was built.
Good to know, thank you. I'll have to read that plaque on the bridge more closely next time. It may have been relocated rather than being authentic.