As I sort of remember, the music for THE WORLD AT WAR is an original soundtrack composed and conducted by Carl Davis, who has an excellent reputation as a film composer. As for THE WAR YEARS, are you possibly referring to THE VALIANT YEARS, a series based on Winston Churchill's books? That is also an original score composed by the legendary Richard Rodgers, who of course was also responsible for VICTORY AT SEA to say nothing of OKLAHOMA, SOUTH PACIFIC, etc.
