Blunden was a cricket fanatic and mentioned that one of his fellow officers, Charlwood, had played for Sussex. In Boyd's book, the protagonist (Lysander Rief) encounters two cricketers who play for Sussex, Vallance Jupp and Joseph Vine.
Rief is sent to a part of the western front near Festubert. Blunden's service on the western front was in the vicinity of Festubert, about which he wrote two poems ('In Festubert' and 'A House in Festubert').
Finally, in both books there are references to the Battle of Aubers (which occurred in 1915 as part of a larger operation that involved a Canadian division).
Here's a passage from Blunden's book:
Such as it was, the Old British Line at Festubert had the appearance of great age and perpetuity; its weather-beaten sandbag wall was already venerable. It shared the past with the defences of Troy. The skulls which spades disturbed about it were in a manner coeval with those of the most distant wars; there is an obstinate remoteness about a skull.Update (June 28): Maybe I was wrong. In the Harper Perennial edition of Boyd's book, Boyd recommends several books about the main topics, settings, etc. of Waiting for Sunrise, but he doesn't mention Blunden. Regarding books about WW1, Boyd recommends Frederic Manning's Her Privates We and Robert Graves' Goodbye to All That.