According to "The MediaBriefing" here,
in their review of Ofcom's recently released "2015 Communications Market Report", here,
The BBC features prominently.

After Google (46) and Facebook (41) , are the BBC's sites (40).
These are followed by Microsoft, Amazon etc, and then
MailOnLine and SKY with (28)
The figures are " Unique audience- millions".

When it comes to "Unique audiences and reach of news services", the BBC leads when it comes to 'Total Digital Audience':-

BBC News 59%
Daily Mail 52%
The Guardian 44%
Telegraph 40%

ITN News appears at number 9 with 16%



Source Commscore MMX-MP survey done in March 2015.