It looks as if Gertrude remarried in 1946. As we can't find a death, it looks as if either the marriage did finish or he was killed abroad in the war.
Gertrude Curzon
Prescot Lancashire
1946 Quarter of registration: Apr-May-Jun
Spouse James Knott
Volume 8B Page 1530
There is another Gertrude Curzon marrying in 1953, but this is probably the daughter.