Complex sentence: In two episodes of the final Brett series, "The Memoirs of Sherlock Holmes", he had leading roles as Mycroft, the first because Watson actor Edward Hardwicke was busy on another film project and the second due to Brett's illness.
Split into simpler sentences: In two episodes of the final Brett series, "The Memoirs of Sherlock Holmes", he had leading roles as Mycroft. The first was due to Watson actor Edward Hardwicke being busy on another film project, and the second was due to Brett's illness.