[Slothie]

I've been looking and discovered the version 5 schematic has pin numbers on the 7445, display and IC11 (80L95/74LS365) whereas on the v1 schematic which I was working from they were not marked, and in some cases the labelling is a bit vague.....
It looks like I have the column drives to the display reversed and also the row lines on the keyboard connecting to the wrong data lined via ic11..... if I'd worked from the v5 schematic originally i'd not have made these mistakes. I'm not sure if that accounts for all the symptoms but I like your idea of using a header and jumper wires while I experiment, I might make a veroboard that plugs into IC11 and I can move the connections around to see what makes sense. The display i'll just cut the column drive tracks an run wires between the display and the 7445 because I'm sure why that is wrong. I will definitely be redoing the board once its working and transferring over all the components to get rid of all my bodges!

I've finally persuaded my phone to upload a picture, the flash washed out the display but I'll get a better picture once I've got the display the right way round!