The deal was effective from December and was exclusively revealed in PrintWeek last year following O2s review of its printing contracts (9 October).
The London-based group will work alongside O2s creative agencies. It will also have teams at O2s sites in Slough and Preston Brook.
Williams Lea and O2 refused to comment on the length of the contract or how much it was worth but added that it was significant.
Our own values and expertise fall closely in line with O2s aim of creating value through high-quality content, services and applications, said Williams Lea business development director Conor Davey.
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