The Smith family sighting.

[AnneGuedes]

It sounds to me as if he had a doubt upon seeing them landing back in the UK as arguidos and thought he ought to share it with the police.

Exactly. He had a doubt, thought 3 days and nights about it and finally decided to share it with the police. A kind of citizen duty. No use to ask his wife to testify.

No use? Wouldn't two witnesses count more? Has she no citizen duty? I don't understand.

A bit sad you don't understand Martin  didn't act as an informer, just someone who doubted. One doubt was enough, the rest was with the police.