Moving this project on despite some misgivings with brickwork. I thought it best to concentrate on one end, so finished the FY which is a zig-zag of MDF followed up by a facia board of same. This was glued, weighted and a few small screws added at certain possible 'rip' points like corners. Note that as was suggested today that I didn't have time to collect together my rare books to use as weights to prove what a worthy railway study buff I am, and just grabbed a couple of toolboxes.
The boards are slightly smaller than I would normally go for at 900mm long. This doesn't mean that by the time all the MDF backscene material is added that they are any easier to lift - I can happily stand on this one with all the box section engineering.