Distraction burglars grabbed hold of a pensioner's crutches then locked him inside his own home during a theft in Watlington.
Police are linking the distraction burglary in Chapel Street on Saturday with two more similar incidents on the same day in Buckinghamshire.
A man claiming to be from the water board - which no longer exists - knocked on the door of an 84-year-old man's house at around 4.30pm.
He demanded to see identification, but the man forced his way inside then grabbed the pensioner's crutches to stop him moving.
A second man was seen going into the kitchen while the first man went into the bedroom.
As they fled with just a bundle of £1 coins they locked the pensioner inside his home with his own keys, leaving them in the lock outside.
Police described the first man as in his late 20s or early 30s, 5ft 5ins, of slight build, with short light hair. He was wearing a dark zip-up jacket.
The second was described as white, in his twenties, 5ft 5ins, and of slightly heavier build. He was wearing what looked like a deerstalker hat.
Police are linking it with distraction burglaries in Chesham and Amersham, both in Buckinghamshire, on the same day.
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