Nineteen pensioners were left facing homelessness after being mis-sold park homes, Hull Crown Court has heard.
William Flannigan, 54, ran a caravan park at Lakeminster Park, near Beverley. He only had planning permission for the chalets to be used as holiday homes.
But he's been accused of telling elderly people that they could live there year-round, and of persuading them to sell up their existing homes.
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According to the Hull Daily Mail, Flannigan often provided interest-free loans to encourage people to move in.
"People were not permitted to use the holiday chalets as their sole residence," David Gordon, prosecuting, told the jury.
"The prosecution case is that he knew this perfectly well, but he put his own financial interests ahead of other considerations, and he dishonestly misrepresented the situation as regards the planning permission to the purchasers of the chalets."
Several of the owners have since been evicted, with no other homes to go to - and some, said Gordon, were left in financial ruin.
The case is expected to last eight weeks.
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And, also last month, Yorkshire estate agent Paul Staniford was ordered by a court to pay more than £7,500 in costs and fines, after admitting advertising holiday homes as permanent residential properties.
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Shelter advises anybody thinking of buying a mobile home to check the owner's site licence. Chalet or mobile home owners only have permission to live on a site all year round if it's described as a 'protected site' or 'park home site'.
"You could also contact the local council's environmental health department and ask whether there have been any problems with the site licence," Shelter suggests.
"Find out if the site owner actually owns the land the site is based on or if they lease it from someone else. If they lease it, ask how long their lease lasts. When their lease ends, your right to stay on the pitch ends."