Britannia ratings reveal why Sky is steering clear of overnight viewing figures

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While the originally reported overnight viewing figures for the series’ first episode were relatively low at 248,000, Sky revealed that the 'first showing' of the episode at 2am (and, more pertinently, its online viewing figures for the opening day) added nearly 300,000 viewers to that figure.

In other words, while few would have actually watched the episode at 2am, the show's availability on demand throughout the day allowed many viewers to watch it before the main 9pm broadcast.

Sky Atlantic series launches (figures according to Sky)

• 5.05m Game of Thrones 2017
• 3.81m Game of Thrones 2016
• 3.05m Game of Throne 2015
• 2.66 Fortitude S1 2015
• 2.36m Westworld S1 2016
• 2.35m Game of Thrones 2014
• 1.88m Britannia 2018
• 1.63m Tin Star 2017
• 1.53m Penny Dreadful S1 2014
• 1.50m Riviera S1 2017

The series as a whole (which went online in its entirety after the first episode) has had almost 7.5 million downloads and views through Sky set top boxes in ten days.

Tin Star by contrast earned 16.5 million downloads and Riviera 20 million downloads – but those figures include their entire broadcast periods and so had longer to accumulate.

As of Friday 26th January, 307,000 people had already watched the final episode of the nine-part Britannia series.

The new data highlights the evolution of TV ratings in recent years, with more and more viewers migrating to watching series through online catch-up services and fewer watching “live” when the episode is first broadcast.

Sky's decision to release the whole series as an online box set as well as show episodes each week is similar to the BBC's policy of releasing recent series such as Requiem and Hard Sun in full on BBC iPlayer, with both broadcasters attempting to service a growing online streaming audience.

This shift also means that programmes that appear to underperform on the night can actually turn in respectable ratings in the long term. In the case of Britannia – which is available to watch and download through normal Sky boxes, the Sky Go app and the NOW TV service – the many ways in which viewers are able to watch the drama makes analysing the show's performance much more complicated.

Sky director of programmes Zai Bennett explained in an open letter last year how the broadcaster was aiming to "completely change" the way it reports on the its audiences.

"The way the industry reports on TV viewing ultimately means that we’re under-selling ourselves. We need to be more transparent," he said, adding that the focus for Sky would be analysing the "seven-day cumulative audience" rather than overnight figures.

Britannia airs on Sky Atlantic on Thursdays at 9.00pm, and all episodes can be watched on Catch-Up through a Sky TV box, the Sky Go app or NOW TV