It is well past six o’clock in Maribor, Slovenia’s second city, and most of the working population is already home for supper. Not so Darko Pihler and Iztok Krambeger, who are locked in conversation in a city-centre office around what appears to be a micro-helicopter, replete with four rotors.

“It flies! It’s a UAV, an unmanned aerial vehicle. These have been around for years, but we have given ours autonomy – that is, some artificial intelligence that means it can fly without continuous human supervision,” says Mr Pihler, general manager of Astron, a start-up high-tech company.