I am having a little more one step forward and two back with this build and it’s my own silly fault. In my eagerness to crack on I hadn’t noticed a photo in the Wild Swan LMS Loco profiles book on the 8F’s that shows the inside of the cab and more importantly the backhead. It seems that I have too much pipe work for my period so some of it needs to come off again.
I am thanking myself in that I took the extra time and effort to make most of the parts removable because that will make redoing it much easier.
This shows how the parts are removable
Below is a crop of the cab photo in the Wild Swan book. The photo is credited to the National Railway Museum and is used here purely to illustrate the differences between what I have done and what I should have done.

