Complex sentence: He was registered not as Anthony, as commonly given, but Antony George Booth, in the West Derby registration district, when his mother's maiden name was given as Thompson (her given name otherwise given as Vera) and she was allegedly of Irish descent.
Split into simpler sentences: He was registered not as Anthony, as commonly given, but Antony George Booth, in the West Derby registration district. His mother's maiden name was Vera Thompson and she was allegedly of Irish descent.