Complex sentence: His father was the son of an Irish farmer who emigrated to London from his home near Skibbereen, in West Cork, in the mid 1960s and his mother is from north London; his mother's maiden name is Treadwell which explains the double-barrelled surname.
Split into simpler sentences: His father was the son of an Irish farmer who emigrated to London from his home near Skibbereen, in West Cork, in the mid 1960s and his mother is from north London. Her maiden name is Treadwell which explains the double-barrelled surname.