Islington Council has fined two landlords £110,500 for providing dangerous and sub-standard housing.
An investigation by the council found 35 breaches of the Management of Houses in Multiple Occupation Regulations at three properties. This left tenants at risk from serious fire safety hazards, overcrowding and disrepair.
At one of the properties, 35 people were living in three two-bedroom flats, while another had no working fire alarm system and dangerous electrics. Tenants did not have tenancy agreements and paid rent in cash.
Cllr Diarmaid Ward, the council's executive member for housing and development, said: 'This case shows that, where landlords and managers put their tenants at risk and provide substandard conditions, they will be held to account by the council and by the courts.
'We are pleased that these two defendants have been brought to justice and handed suitable fines for their offences.'
Landlord Arun Bajaj, 60, was found guilty of 15 offences and was fined £100,000. Antonio Ferraiuolo, 57, was found guilty of 35 offences and was fined £10,500.