Thanks. I have looked for her on the 39 Register under her maiden and married names (married in 1936) but can't find her. I've also tried the addresses I have for 1936 and 1942 but again nothing. I know people moved around a lot at the time, but this couple seemed to have dodged the census completely.
I can also find no subsequent marriages under her maiden or married names. Seeing as she was only in her 20s when her husband was executed, that seems a little unusual, unless she was traumatised by her marriage. So, I'm beginning to suspect she took on a new name.