Axel Springer did not complete due diligence on the Telegraph before sealing its £575m takeover , with sources saying the German media company could struggle to recoup its eye-watering investment as the titles shift toward less-profitable digital subscribers. To wrap up the deal quickly, Mathias Döpfner, the chief executive of Axel Springer , decided to forgo the usual extensive due diligence process to vet the value and prospects of a company, according to multiple sources. Axel Springer last month swooped to buy the Telegraph titles from UAE-backed RedBird IMI, thwarting a £500m deal agreed with Lord Rothermere , the owner of the Daily Mail by paying a substantial premium. RedBird IMI, which was forced to put the titles up for sale after the British government passed a law limiting foreign states or associated individuals from owning newspaper assets in the UK, called the negotiations “swift and efficient”.…