Complex sentence: For a time he claimed that he was the original Lord Haw-Haw, he did have an upper-class accent, but he later decided that it was probably Mittler whose voice Barrington had heard.
Split into simpler sentences: For a time he claimed that he was the original Lord Haw-Haw. He did have an upper-class accent, but he later decided that it was probably Mittler whose voice Barrington had heard.