Frosted windows have been placed in BT phone boxes across South Kensington to help tackle prostitute carding.

A total of 20 phone boxes in the SW7 area, thought to be the ones most targeted in the borough, have been frosted to prevent passersby seeing the sexually explicit cards.

It is the latest tactic in the battle against calling cards, use of which has already fallen in the area over the past 12 months.

BT has been working with Kensington and Chelsea Council and people living in the area for over a year in a bid to tackle the scourge and their efforts, which include regular monitoring of phone boxes and cleaning, have already resulted in a dramatic reduction in the amount of cards.

The Kensington and Chelsea Community Policing Team has also undertaken a number of enforcement operations targeting carders , the most recent of which saw seven arrests made in July.

The most prolific carders have been given Criminal Behaviour Orders, which ban them from placing cards in phone boxes for five years.

Brothels have also been raided and searches carried out for people trafficking.

Councillor Gerard Hargreaves, cabinet member for Civil Society, said: “Residents have rightly complained about the impact carding in phone boxes has on the area in which they live in.

“We have been working closely with BT, the police and residents to identify the most affected boxes and look at what can be done to deter this practice.

“The work has already had a real impact. The message is out that we are actively tackling this problem, that carders and brothels are being targeted and this can end in court. The frosting of these phone boxes is the next step in our campaign and I hope we will soon see an end to this problem.”

Anyone who spots cards for prostitutes in a phone box should not remove them, but let the council know by using the app RBKC Local, emailing or calling 020 7361 3001. The police can also be called on 101.