The timescales are implausible. The Series begins in about 1905, and Emma seems to be about 20. However, the present day is set in the 80s. This would make Emma well over 100 in the present day and her eldest child in her 80s - none of them are old enough.
The transatlantic liner Queen Elizabeth on which Paul McGill says he is booked to go to the USA in 1939 was not completed until 1940 and did not enter commercial service until after WW2, about 1946. He may have meant the Queen Mary.