Illicit booze and more than people illegally crowded into flats were found during a raid on a pub by police, council and customs officers.
The raid on The Masons Arms, in High Street, Edgware, this morning was part of a joint day of action between Harrow Police, Harrow Borough Council and partner organisations.
Above the pub 13 single room flats were found housing 21 people.
The property only has permission for nine people to stay there under its house of multiple occupancy licence.
As a result of the find this morning Harrow Borough Council says it will review the licence on the property.
Council leader Councillor Susan Hall said: “The council will do all it can to stop people from being exploited in these properties.
“There has been a breach of the licence here and we will take robust action. The police are taking robust action and we must do all we can to support and help them.”
Officers from Trading Standards and HM Customs found more than a dozen bottles of alcohol at the pub on which duty had not been paid.
Police say they will call for a review of the alcohol licence for the establishment with the council.
Cllr Hall added: “Today has been another great example of our work with partner organisations to help make Harrow a safer place.”