My mother redoubled her efforts.
across the road from their house there is a boundary hedge with a drainage ditch in front of it. The ditch is full of thistles and nettles and long grass and an ideal place to stage a stake out. Embedding a camping chair in the ditch and dressing warmly, my mother set the alarm again, waited for the milk to be delivered and then went over the road and settled herself into the ditch at about 3am.
Nothing happened
Until 5am when the paper boy came along to deliver the newspapers.
Mum was concerned that when he passed where she was hidden, the boy might see her and be startled, so when he drew near she called out to reassure him
Hello... Hello there ... It's only me!
The boy looked around to see where the voice was coming from - but she was hidden from view and too deep in the ditch and too cold to get up and reveal herself
Dad called her in for breakfast at 6.30 and no more milk went missing and the matter faded away ...
... Until a few weeks later the postman came to the door and said
you'll never guess what?... then showed her a video on his phone of a large retriever jogging up the road, carrying a square plastic milk bottle in his mouth.
(continued from previous post)