A disappointment on two fronts: the author and the subject.
Egremont has a reputation as a quality writer but the approach taken here was a grind, it seems from the footnotes largely informed by Spears' and his wife's own papers and letters.
Particularly in the first half of what seemed a very long book too much was spent on that insipid and, as it would now be referred to, codependent relationship. Frequent and long quotes from their letters detracts rather than adds.
By comparison Spears' own writing style, from his 'The Picnic Basket' is fluent and captivating.
As for the subject - he comes across as thin-skinned, greedy and self-centred. I've no reason to doubt the treatment but it doesn't make for pleasant reading.
He played a crucial role as liason officer in the critical time of 1914 (Mons, Le Cateau) but that gets skimmed over, as if the author didn't want to do military history. John French gets mentioned (as mentor) but was there any interaction with Smith-Dorrien and Haig?
And for the later years in the war when the politics of the British and French high commands was so relevant this is not treated in sufficient breadth or depth either. It just isn't enough to say he and Henry Wilson hated each other.
In the interwar years it was interesting to see his path cross with Robert Bruce Lockhart as commercial attache in Czechoslovakia, plus a business relationship with the dubious Sydney Reilly.
The WW2 coverage of the relationship with De Gaulle is interesting, as is his time in the Levant but on the latter again too much from the personal worms-eye view of Spears psychology rather than framing his activities and behaviour within the overall political situation vis-a-vis Whitehall.