Credit checking firm Experian has taken a further step in its strategy to increase digital marketing activities with the acquisition of a majority stake in social media marketing tool provider Techlightenment.Techlightenment, which was founded in 2007 and is based in London's trendy Shoreditch district, part of the area prime minister David Cameron said he wants to become Britain's 'Silicon Valley', provides social media marketing services to companies such as the drug group GlaxoSmithKline and the shoe brand Dr Martens. It is expected to post revenues of £5m in the year to 28 February. It works with social networking sites such as Facebook and MySpace."The acquisition is a further step in Experian's strategy to grow its digital marketing activities," said Experian. "It extends Experian's capability into the increasingly important social media channel, adding to Experian's presence in the online, email and mobile channels."