Gelardi's book is excellent. It does point out the anger felt by Constantine and Sophie (and other family members) towards the Allies--at least their governments. This is why I think it more complex than pro or anti this or that. The Allies, especially the French, in the Greek royal family's eyes treated the monarchy abominably and were at the root of the propaganda against them--propaganda that nearly turned deadly for the family (and indeed deadly for some of their retainers). Their anger at their treatment by the Allies had to occasionally at least contrast with the behavior of the Austro-German axis no matter what one's personal feelings. They believe, correctly, that, once Greece refused to capitulate the monarchy needed to be overthrown. This was obvious to George V as well who believed the British govt had allowed 'France too much to dictate a policy, and that as a Republic she may be somewhat intolerant of, if not anxious to abolish, the monarchy in Greecce.' This was written to the British foreign secretary Edward Grey in Sept 1916. Soon after the British minister in Athlens remarked that Constantine 'spoke...more bitterly than ever' to the Russian minister about his treatment by Britain and France, especially France.
In December 1916, following Allied bombardment, Tino wrote to GV that while he knew the King personally didn't believe they harbored plots, he entreated them 'do not push us to despair...we have been cruelly treated owing to lying'. Sophie, meanwhile, fired off a series to telegrams to Berlin at the time--they were published by the Greek government in 1919. Some of these telegrams were to her brother and they continued on describing bombardment, blockade, food shortages. One telegram to the Kaiser said 'How much I suffer!...May the infamous pigs receive the punishment which they deserve!'. Some quetsion of the telegrams was later called into question by Prince Nicholas in 1928 as perhaps revealing only partly the truth but it wouldn't be surprising for someone in Sophie's position to be pushed towads a country that was shelling and starving her people and trying to ensure the overthrow of her husband. These telegrams covered Dec 1916 to Feb 1917. Nicholas defended his sister-in-law's writing to her brother as the act of a desperate, mortified woman--not one coldly plotting with her brother. While assigning most blame to France, Princess Helen (daughter of Sophie) said te family felt stabbed in the back by a dear, trusted friend' (Britain).