RE-installed the battery tray (this is really part of my front diff replacement saga but I will save it for what is, hopefully, the final "wrap up" installment). This was my 2nd attempt, a couple of weeks ago I didn't get round to it 'til too late in the day & gave in to failing light & falling temperatures. Today, I nearly gave up twice (perhaps not really in the right frame of mind), I couldn't believe what a pantomime it was: it's such a difficult, clumsy shape & seems much too large for the available space, It was so long since I removed it, I couldn't remember what went where or how I'd done it and it's complicated by the LPG (think CNG) conversion which means not only is there more wiring & plumbing in that fairly crowded corner but one component is on a bracket bolted the back "wall" of the tray & its own ECU is bolted to the front panel in front of where the tray goes. Anyway it's back in now - with 3 bolts instead if 1 (I found one lodged down on the frame, although didn't recognise it for what it was at the time & used an M6 flange nut & repair washer on the remaining stud.
However, I'm not happy with where the harnesses are routed so will remove the PDC next weekend (I hope that's all that'll be necessary) & tuck all that wire under it, instead of running along the front lip of the tray.