Well I thought I'd finished the PWA, but as I was fitting the excellent railtec transfers, using Humbrol DecalFix (which is a first for me and found it much easier), using the reference pictures on @hmrspaul superb site, I realised the underframe has plates over some of the gaps. Just contemplating to try and use painted inkjet acetate sheets....
The bogies supplied seemed to be too narrow so have used English Steel ESC-1 from the N gauge society - which I don't think are 100% correct, but they'll do for me