A 'beds in sheds' structure in the back garden of a family home was torn down following a council investigation.
The single-storey outhouse in Rayners Lane was demolished this week following an investigation by Harrow Borough Council planning officers.
The owners were given an enforcement notice for the structure, which was built without planning permission.
Cabinet member for planning and development Cllr Stephen Greek said: “This was a flagrant abuse of planning rules, with people living in cramped and unsuitable conditions.
“Cases like this underline why the work of our planning enforcement team is so vital, and why it is so important that we have given them extra support to crack down on this type of abuse.
“Rogue landlords should have nowhere to hide in a cleaner, safer and fairer Harrow."
Earlier this year the council commissioned a remote controlled plane to take thermal images of the entire borough.
Before the operation, planning officers estimated there were 75 cases of unauthorised 'beds in sheds' in Harrow.
Now there is a list of 319 potential cases identified in the evening flight, during which a thermal imaging camera was used to take aerial shots of the borough.
Earlier this week, Mayor of London Boris Johnson praised the work of Harrow Council leader Cllr Susan Hall in tackling the problem of beds in sheds during his Mayor’s Question Time.