Vodafone and Three agree merger to form UK’s largest mobile operator

Deal to combine firms' British telecoms networks likely to face competition scrutiny amid union calls for merger to be blocked

Vodafone and the owner of Three have agreed a deal to merge their British telecoms networks in a move that will create the UK's largest mobile phone operator.

The two companies are the UK's third- and fourth-biggest operators respectively. The newly combined company will, if the merger is completed, have more than 27 million subscribers, leapfrogging EE, owned by BT, and Virgin Media O2, owned by Spain's Telefonica and the US-listed company Liberty Global.