I found this ok. 
Being an amateur second world war historian, I am easily pulled into a historical fiction based in that time and environment. I enjoyed the story in general, however I found it far too ‘surfaced’. There was no depth. Details, emotions and impacts were skimmed over. That doesn’t work for me personally. I want to drown in adjectives so I feel that I am there and experiencing it all myself. 
Also, I really thought that the story would have been fully set in the time of the war, not going straight into the 1970’s, throughout the rest of their lives and jumping ahead by years at a time. Although, it was also nice to see Alex’s (and Richard’s) journey. But I want more than nice. 
I think that this could have been a trilogy, if the story was slowed and filled with the depth that it deserved.