Have just finished reading The Stranger's Child by Alan Hollinghurst.
The paperback has 560 pages, and the novel is so well-written that at no time did I feel bored with it.
Ostensibly about a poet (obviously based on Rupert Brooke) it is actually a literary detective story comparable to AS Byatt's Possession.
Alan Hollinghurst is a seditious writer - he subverts the country house Brideshead genre, he undermines the reputation of Rupert Brooke, he exposes the myth-making surrounding the Great War.
The first section is slightly cloying (home life among the Honeychurches I thought), and I did not enjoy entering the soul of a bank clerk, but it is a fine book.