A British TV monitoring group is trialling technology that will enable it to tell how many people are watching shows on Netflix.

Netflix has a string of popular hits, but it has always refused to reveal how many people watch each programme.

Now the Broadcasters Audience Research Board (BARB) is piloting new technology that will let it monitor Netflix’s viewing levels without the service’s co-operation.

Around 5,100 homes have BARB boxes that record which programmes are watched and are used to generate viewing figures. Some are now trying out router meters to determine the number of hours spent watching services like Netflix.

BARB is also experimenting with new technology that could one day provide viewing figures for individual Netflix programmes.

Justin Sampson, BARB chief executive, said that it was vital for TV measurement companies to keep up with changing viewing habits, and the technology would allow it to understand the scale of Netflix.

This is not the first rating company to attempt to scrutinise the firm, as in October 2017, US ratings company Nielsen announced that it had developed a system for calculating how many American viewers watch Netflix episodes by using audio recognition software.

According to Nielsen, 15.8m people in the US watched the first episode of Stranger Things 2 in the three days after its October launch, while the first episode of the latest season of House of Cards attracted 4.6m viewers in its first week.

The figures however were strongly disputed by Netflix, which claimed they failed to monitor viewing habits on mobiles or downloaded content.

It is understood that BARB could encounter a similar roadblock.