Complex sentence: She never returned to parliament; after her Wallsend defeat she was adopted as the Labour candidate for Reading, but when it became obvious that the election due for 1940 would be delayed indefinitely by war, she resigned her candidacy.
Split into simpler sentences: She never returned to parliament, although after her Wallsend defeat she was adopted as the Labour candidate for Reading. When it became obvious that the election due for 1940 would be delayed indefinitely by war, she resigned her candidacy.