The decision by the Times to task a Conservative MP and Brexit campaigner with the UK’s first post-election interview with Donald Trump may have drawn criticism in Britain, but Michael Gove’s German co-interviewer is also a controversial figure.

Since joining Axel Springer, Germany’s biggest publishing house, as a trainee in 1985, Kai Diekmann has been one of the most powerful – and colourful – operators in media and politics. In particular, his close links to conservative politicians have often made him a bête noire for the German left.

After working in various editorial roles for Axel Springer’s two flagship publications – the world’s bestselling printed newspaper outside Asia, Bild; and the more upmarket broadsheet Die Welt – Diekmann took over as Bild’s editor in 2001, eventually moving on to become publisher of the Bild group.

Diekmann’s fans insist he managed to wrench the right-leaning tabloid into the political centre – directing its ire as much at rightwing populists of the Pegida protest movement and the AfD as at its old enemies among the Green party and the 1968 student movement, though his critics continued to find problems in his close ties to conservative politicians.

Former German chancellor Helmut Kohl was one of the best men at Diekmann’s wedding to columnist Katja Kessler in 2002; in turn, the newspaper editor was one of the best men at Kohl’s second marriage six years later. The offices of Taz newspaper are adorned with a mural containing a caricature of a naked Diekmann, with his penis stretching all the way to the building’s fifth floor – fallout from when the Bild editor sued the leftwing paper over a satirical column.

In the autumn of 2012 Diekmann moved to Silicon Valley for almost a year to explore the digital media economy, ditching his prim look for a hipster beard. On Monday, German media speculated that his connections to Californian entrepreneurs may have played a part in securing his interview with Trump.

A spokesperson for Axel Springer would only confirm that Diekmann had organised the interview in person. In an interview with Frankfurter Allgemeine Zeitung, the 52-year-old said “for me it has in the last 16 years always been important that I arrange and conduct interviews in person”.

The journalist’s scoop comes as he is due to depart from the publication that made his name. In a tweet, Diekmann described the Trump interview as his “leaving present”.

On 6 January it emerged that a court was investigating Diekmann over the alleged sexual harassment of a Bild employee, though the company insisted his departure was unconnected to the incident.

Diekmann told Frankfurter Allgemeine that the conversation with Trump had been “the most unusual interview” of his career. “Because the answers were not polished out of a washing machine, after tons of communication advisers had scrutinised them.”

“After talking for an hour,” Diekmann said, “you got the impression that Trump views the United States at heart as a big business which isn’t working so well anymore and is only producing bad figures. He’s the new CEO who has to fix things.”