You plonker, MM. His wife was looking for him. So either he lived there with his wife and was the occupant of the house, or his 80 year old wife was also being cruelly used by the wealthy owners, as an au pair, perhaps.
The newspaper's 'gardener' label refers to his activity at the time, not his occupation.
Anyway, a £200,000 house hardly suggests wealthy owners.
BBC had an average price for a detached house at about £350,000, so a £200,000 detached house is rather at the lower end of the housing market.
In fact, I'd guess you be hard pressed to find a detached house under £200,000.