Two landlords and two tenants were fined a total of over £11,000 after losing their appeal against housing convictions concerning property management.
Landlords Zulifqar and Rozina Bhatti were found guilty by a court in Harrow of management regulation breaches, failure to licence and a failure to respond to statutory notices on January 12 this year.
Bhatti was fined £6,100 and asked to pay costs of £4,800. His wife was convicted of two offences for failing to respond to statutory notices, and sentenced to a conditional discharge for 12 months.
Meanwhile two rent-free tenants - brothers Adeel and Raheel Butt - were fined £200 each with £175 costs each on top.
They were living rent-free in a four bedroom mid-terrace house with other rent-paying tenants in Wembley, when enforcement officers raided the property in June 2016.
The landlords had allowed the brothers to live without paying rent because Raheel Butt used to work for Zulifqar Bhatti more than 10 years ago.
When the case was heard at Willesden Magistrates Court in January last year, a fifth defendant - Ian Taylor, who was a friend of the landlords - was also fined £400 for failure to respond to a Brent council investigation, as well as £530 in costs.
He was the only one of the five defendants who did not appeal his sentence.
At Harrow Crown Court, the judge told the Bhattis and the Butts that they had wasted enough of the court's time.
A spokesman for Brent council said:"Obstructing a council investigation into housing breaches and a failure to licence is a serious offence. All landlords who rent HMOs in Brent need to stick to the law and license their properties. Anyone who obstructs a council investigation into housing breaches may end up in court slapped with hefty fines and costs."