Good to see progress on a very good quality Lathe. S & B made Tool Room standard machines and yours will, I'm sure, produce very good results.
The E H Jones Plate is the Retailer/Distributor of Machine Tools in the UK much of the first half of the last Century.
As a coincidence, I have an item which covers both EHJ and the name 'Victor' on your Chuck from 1948 (about the same age as your Lathe) Here's some images-
If you're not aware, the 'Smart and Brown' Company does still exist .....in a different form, but you can still obtain parts and information you may require. Here is a link-
Bracehand Ltd
Here are links via my favourite Old Engineering Search Site to some possible info you may be interested in-
VICTOR (general search only shows up a modern Taiwanese Company)
EHJ
Lastly, I assume the 'Engineers Blue' marks are on the mating face of the Lathe Tray/Bed to Stand?. Used to identify the amount of contact between them. Progressively scraped as you say, or filed until an acceptable amount of contact and level was achieved.