Vodafone and Three have completed their merger two years after initial proposals triggered a lengthy investigation by the UK’s Competition and Markets Authority (CMA).

The combined business, named VodafoneThree, will host more than 27 million users – making it Britain’s biggest network and reducing the number of competing companies in the sector from four to three.

The CMA originally halted the deal over concerns that reduced competition could negatively impact consumers. In December, following an 18-month investigation, it finally said the firms could proceed as long as they sign a binding commitment to invest billions in Britain’s 5G infrastructure.

As part of its announcement, VodafoneThree said it will invest £11bn over the next 10 years in its 5G network, starting with £1.3bn over the next year to accelerate its network deployment. This includes a broader roll-out of “standalone” 5G networks. These are considered superior to other implementations of the technology, which partially...