I like your descriptions of the characters and of the setting. If I'd written it I'd have tried to prepare for the twist without giving too much away.

I'd mention a small ball lying in a corner of the sitting room. Voss could think the old lady has a granchild who called and forgot to take the ball home. Then at the end she says "Arthur's not my husband, he's my cat. That's his ball in the corner." That prepares for the twist without making it too obvious.

The captain stealing Vosse's thunder rings true.
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