Joel Salem, 66, of Highview Gardens in Finchley, was penalised after failing to comply with a 2010 planning enforcement notice.
Judith Veronique Robinson-Dadoun, 58, formerly of Brampton Grove in Hendon, was also found guilty of breaching the notice, which concerned a property converted into seven flats when only four were permitted.
In 2020, both were convicted at Highbury Corner Magistrates’ Court, yet they continued to let the unauthorised flats for several years despite enforcement action.
The Court of Appeal on Friday, December 19, 2025, dismissed their appeals.
Councillor Adam Harrison, cabinet member for planning and a sustainable Camden, said: “This was a complex and long-running planning enforcement case.
“The dismissal by the Court of Appeal has reiterated that we will not accept substandard accommodation and that we will always strongly pursue the breach of planning enforcement notices for as long as it takes.
“These developers sought to make as much money as possible from residents living in poor quality accommodation.
“We will not accept this sort of behaviour, and this sends a strong message to other landlords and building owners.
“You need to comply with planning rules, and we will stand with our residents who deserve safe, good quality homes.”
The Court of Appeal upheld a £262,500 fine and £185,258.73 in costs for Mr Salem, and a £70,000 fine and £61,752.91 in costs for Ms Robinson-Dadoun.
Earlier confiscation orders were also confirmed.
Lord Justice Fraser described Mr Salem’s conduct as “egregious” and emphasised that planning enforcement exists to protect tenants from exploitation.
He said: “These defendants ignored repeated warnings and continued to profit from unlawful lettings over many years.
“The very significant costs arose as a direct result of the defendants’ conduct.
“It would be wholly wrong for Camden’s taxpayers to bear that burden.”
