Londoners letting homes on short holiday stay sites have been warned to follow the rules as an investigation is launched into 1,200 properties, finding evidence of parties, sex work and overcrowding.

Westminster City Council says 75 breach notices have already been issued over short-term letting on sites such as Airbnb and HomeAway in the central London borough.

It has launched an investigation into the problem, and found multiple parties, music events, incidents of serious overcrowding, and sex work all occurring within nightly lets in the borough.

The council says there are some households in the borough letting their properties to short term guests across almost every night of the year.

Anyone letting a room or property more than 90 nights a year without the proper planning permission from their local authority, can face a conviction and unlimited fines.

What's happening in west London?

Airbnb complies with UK laws and its site doesn’t allow people to offer their properties for more than 90 days a year to fit unless they have the proper planningn permission.

However, the council says landlords and tenants subletting get around Airbnb's rules by offering the rooms on multiple platforms like HomeAway.

Letting out a property on sites like Airbnb, which has a dedicated safety department, for more than 90 nights a year is considered to be commercial activity by the government, and requires planning permission from the local authority.

According to Inside Airbnb, it is estimated that in Westminster there are 4,703 Airbnb listings, comprising 3,284 entire homes, 1,378 private rooms, and 41-shared rooms.

Westminster Council has invested £200,000 in a new Housing Standards Taskforce, which is not only collecting evidence on properties suspected of breaching the 90-night limit, it also targets landlords renting out sub-standard properties.

Council leader Cllr Nickie Aiken said it was possible some people letting out rooms or their homes on short term stay websites may not know the 90-night limit exists.

But she warned the council was taking a tough approach, adding the proliferation of short term visitors were upsetting residents in the borough.

“We have no problem with people earning a little extra money by letting their home considerately within the limits, but those who are breaching the 90-night limit and letting 365 days a year are a blight on the lives of our residents,” she said.

Airbnb says the council has not brought to its attention any issues in the borough.

An Airbnb spokeswoman said: "Inappropriate, illegal or disruptive behaviour has no place on our platform and we permanently ban bad actors from our community.

"Each and every Airbnb reservation is scored ahead of time for risk to prevent incidents from happening in the first place.

"Over two million guest arrivals stay in a listing on any given night and negative experiences are incredibly rare."

As part of Airbnb's system hosts can provide guests with house rules ahead of a reservation being booked, which explicitly outline whether events or parties are allowed.

HomeAway has also been contacted for comment.

What are the penalties for illegal short-term lets?

  • Conviction in the magistrates’ or crown court can lead to an unlimited fine for non-compliance with the requirements of an enforcement notice
  • If you are issued with an enforcement notice, it will be recorded as a charge on the local land charges register which can affect the ease of a future sale or financing of the property.
  • Westminster City Council plans to quiz people letting short-term on whether “commercial” letting, for more than 90 nights a year, invalidates their mortgage, and home insurance, and possibly even the entire block's insurance.