This seller has a lot more ww1 US books for sale, he is in the us but ships to the UK.
Keith
https://www.ebay.com/itm/Handbook-of-the-5-Ton-Artillery-Tractor-Model-1917-WWI-Ordnance-Manual/264095623283?_trkparms=aid%3D444000%26algo%3DSOI.DEFAULT%26ao%3D1%26asc%3D55165%26meid%3D283099ee8b254a648d2185abf08a0aad%26pid%3D100752%26rk%3D3%26rkt%3D6%26sd%3D264095627664%26itm%3D264095623283&_trksid=p2047675.c100752.m1982