Van parked and idling engine. Driver away from vehicle

A white Ford Transit van was parked outside 4 Paddington Street with the engine idling this morning around 9:17am. The driver was away from the vehicle. There was a man sitting in the passenger seat, so I asked him politely to turn off the engine. He said he couldn't and that the van wouldn't re-start if he shut off the engine. He then appeared to be trying to call the driver on his mobile phone while I photographed the reg plates.