Games of Thrones, S7 E1 achieved Sky's highest ever viewing figure of 4.7m

"The first episode of the seventh season of Game of Thrones has continued its unprecedented run by recording the biggest consolidated audience for a programme ever on Sky with 4.7 million.
The episode. entitled Dragonstone, almost doubled its audience in the week after it launched, adding an additional 1.85 million to the original 2.8 million who watched it on July 17th. This stand out performance also meant the episode secured the fifth biggest programme audience of the year in Sky homes, outperforming Sherlock, Call the Midwife and Line of Duty.
The 4.7 million figure is made up of those who watched the 2am simulcast (live or on demand) or the 9pm transmission on July 17th, those who have chosen to catch up over the past seven days through on demand on Sky Atlantic or online streaming service NOW TV, and customers who recorded the episode and watched it back. A further 729,000 downloads and streams of the episode were made via the Sky Go app, with this expected to increase further over the coming weeks. Sky Atlantic has seen a huge increase in Game of Thrones audiences year on year with a 31 per cent increase on the opening episode of season six last year (3.56 million consolidated)."

Source:  Advanced Television, 27th July 2017

Note - I'm assuming that the numbers aren't completely de-duplicated - e.g. people watching at 2am but then also watching again later on Sky Go.