"The possibilities for apps to make the streets an active, reclaimed playground in which to have interconnected fun are boundless.

"Increased physical activity is a tantalising side effect."

Pokemon Go players use a smartphone in a virtual scavenger hunt for cartoon characters, but in real locations.

The arrival of the Nintendo-designed game was dogged by negative reports of teenagers getting lost down caves while searching for the virtual monsters, and even causing gunfights in US cities.

But Dr McCartney said those stories masked the benefits caused by a game that was getting people outside.

“We never hear about the things that didn’t happen,” she said.

“The heart attacks prevented through more exercise, or the vitamin D deficiency that geeks have avoided, blinking in the sunlight while catching a Pikachu monster.”