I can only tell you a little, but it may help.
At the age of 13, my father (a Londoner) won a scholarship to Bolt Court Technical School in Fleet Street, London, (which later became London School of Engraving & PhotoLithography, and later still became the London College of Printing).
My father went into the Photo-Lithography side, as he was keen on photography and printing, eventually he became a lecturer in photo-lithography.
One of his friends at Bolt Court was in the engraving side and eventually worked in London, where he did engraving for bank notes, which is probably more the side you're interested in, but I'm afraid I know nothing more!
Another boy at that school was the well known Kenneth Williams, who studied cartography, but was more interestd in clownig around, and as we all know, he chose that over a career as a cartographer!
During WWII the juniors section of Bolt Court had to be re-located out of central London, and so it moved to Bicester in Oxfordshire. But in 1943 when my father was 15, and of school leaving age, he was no longer of evacuee status, and so had to continue attending Bolt Court in Fleet Street, London. But as the school grew, they had to find new premises, and it re-located away from Fleet Street.
There was a Bolt Court old boy's organisation, and if it is still in existence they may be able to supply you with information about photo engraving as it was done in those years you are interested in. Otherwise how about writing to the the London College of Printing? If it still exists?!!
Sorry I can't be of more help.
DG