Complex sentence: Sir William Haley, the BBC's Director-General, had already met Jacob during preparations to report the news of the D-Day landings and was aware that his political contacts (Churchill in particular) could be valuable.
Split into simpler sentences: Sir William Haley, the BBC's Director-General. Haley had already met Jacob during preparations to report the news of the D-Day landings and was aware that his political contacts (Churchill in particular) could be valuable.