If it's any help, I bought my UK early DT books from Greg (Shibus) and he was very well versed in the UK firsts. In fact, he educated me with regards to the PB's being the true firsts and I took him at his word (which I have always found to be very reliable). My first 3 UK DT's are Lt Blue, Tan & Dark Blue on the spine illustration all by Sphere. H&S did produce a HC W&G which I have, so its only the first three to my knowledge.
In any case, you may want to PM Shibus and ask him. I trust his judgement.
Hope that helps.