O2 (UK) BT subsidiaries: Esat Digifone in Ireland, Viag Interkom in Germany and Telfort Mobiel in the Netherlands. The rebranding was supported by a European advertising campaign, which began on 16 April 2002, across all four countries, at a cost of £130 million. The main launch campaign ran from 18 June and was developed by Vallance Carruthers Coleman Priest, working alongside brand consultancy Lambie-Nairn, creators of the "O2" brand identity. In March 2005, mmO2 restructured its shares and the company was relisted as O2 plc. On 30 November 2005, O2 agreed to a takeover by Telefónica, a Spanish telecommunications company, for £17.7
O2 (UK) UK. The deal was subject to regulatory approval. The European Commission decided in December 2015 not to refer Hutchison's takeover of Telefónica's O2 business in the UK to the country's Competition and Markets Authority, which had asked to be allowed to investigate the planned acquisition, arguing that as the British competition regulator, it – and not the Commission – should have the right to rule on the 'transaction', which it argued 'threatens to affect significantly competition in the UK retail mobile and wholesale mobile markets', claiming that its investigation of the takeover would 'avoid duplication and fragmentation'. On 11 May