Sky has held talks on a possible strategic partnership with O2 after approaching the UK mobile network’s Spanish owner, Telefónica. The talks come as BT, arguably Sky’s biggest rival, negotiates a potential £12.5bn acquisition of mobile operator EE. That deal would give BT the ability to offer customers a “quad play” package of home phone, broadband, TV and mobile. Sky does not want to risk being left as the only big UK broadband provider that cannot offer a quad play package.