It’s 1879. The putative history is that the RLR was first incorporated as a Tramway before being reincorporated as a light railway after the Light Railway Act was enacted. The original date was going to be 1889, but I didn’t have enough “8’s” left on my Slater’s letter sprue to write that so hence now 1879 It also pushes the date closer to when cast iron would be the choice design, although I believe short arched designs with lighter loads in cast iron were used later than in other circumstances. I also have made up a SHL resin roll top girder bridge and an American made (Hampton Garden Railway Models marketed in UK by Cain Howley) plate girder deck plate girder with no rivet detail (so presumably “welded” construction). I am struggling with a back story for that combination!
I am spending Sunday morning drinking frothy coffee and contemplating how to make shoes to fit the bridge and whether or not to model newel posts for the end of the bridge.
Andy