The number of garden gnomes is set to increase by 1.4 million this summer as people look to "cheer up" their homes, a report has predicted.
But the expected rise in the gnome population could also spark more thefts, warned Halifax Home Insurance.
One in four people have been the victim of a "gnomenapper", leading to a thriving online market, with some ornaments selling on auction sites for more than £600, a study of 2,000 adults by the firm showed.
Martyn Foulds, senior claims manager at Halifax Home Insurance, said: "As gardens become more of a feature of people's homes and the contents increase and become more valuable, owners should make life as difficult as possible for opportunist green thieves.
"They can do this by keeping their gnomes and other garden items out of sight or under lock and key when the property is unoccupied. As this year's 'must have' home accessory, the humble garden gnome is an easy target."
The research showed that gnome owners were usually aged 65 and over, although an increasing number of younger people were considering buying one.
Oxford is said to be the gnome capital of Britain, with a quarter of residents owning the ornaments, while thefts are most likely in Edinburgh, Manchester, Birmingham and Southampton.