Secrets From Norway

Two young people meet in Norway in the summer of 1940. The man, Colin, is a British RAF pilot who is trying to build an airfield for the Allies as part of their vain attempt to prevent the Nazi occupation of Norway; the woman, Ingrid, needs to get to Britain with a valuable burden that she wants to keep out of the clutches of the advancing Nazis. Teaming up together, they make a perilous voyage to Scotland where Ingrid is persuaded to join the Special Operations Executive, tasked with causing sabotage behind enemy lines.
Colin eventually returns to flying duties but is killed in an accident just after WW2. He has fathered two sons who are very close to each other. One contracts Muscular Dystrophy in later life; the other has a beautiful, lawyer partner who initiates the uncovering of mysteries surrounding Colin and Ingrid.
How did Colin get to be awarded an Order of the British Empire when only twenty-six years of age?
What was it that Ingrid brought out of Norway?
What were the two of them doing after they landed in Scotland?
What is the significance of Arisaig House where they both lived for a while?
And how do the answers tie into the death of Colin's son?