Suddenly she looked up suspiciously at her husband.
"Henry," she said, "I've just received a letter from mother saying she isn't accepting our invitation to come and stay, as we do not appear to want her.
What does she mean by that? I told you to write and say that she was to come at her own convenience. You did write, didn't you?"
"Er, yes, I did," said the husband. "But I, I couldn't spell 'convenience,'
Spoiler:
