Image copyright Torquing Image caption More than 12,000 people gave a total of £2,335,119 to fund the drone via Kickstarter

It was Europe's most successful Kickstarter project - but now the Zano mini-drone is in deep crisis.

Last night, the former chief executive of Torquing Group - the firm behind the Zano - resigned. That left the thousands who had backed the firm with more than £2m a year ago in despair.

Ivan Reedman, the engineer driving the design of the mini-drone, explained why he was going in a post on a Zano forum.

"My resignation is due to personal health issues and irreconcilable differences," he wrote.

Reedman, who stepped down as chief executive to become R&D director last year after new investors bought into the business, had been the only executive to engage with worried backers over recent months.

"To say I am devastated pales when compared to what I am feeling," his statement said.

Media playback is unsupported on your device Media caption Rory tested the Zano drone ahead of its release

Those who had backed the project reacted with sadness.

"Fingers crossed Zano can continue," wrote one backer, "for the benefit of everyone (including me) that has invested their hard-earned money."

But many of the more than 12,000 backers have already despaired of receiving what they were promised in Zano's Kickstarter campaign.

Its promotional video showed the tiny drone following a mountain bike down a wooded path, and a cliff diver plunging into the sea, all the while capturing high-quality video.

But when I visited the Zano team in Pembroke Dock, south west Wales in August, it was already clear that the project was in trouble.

I got the first demonstration of the drone and it was not impressive, staying airborne for only a few minutes, colliding with walls, and delivering very poor video.

Reedman promised that these problems would be ironed out with later software upgrades, and that the priority was to start delivering the device to backers.

Image caption The first batches of Zanos have not provided all the functions that had been promised

Since then, some backers have received their drones. But as far as I can see, none has been happy.

"Give me back my money, let me put it towards a drone that works," was one comment on a Zano Facebook forum.

An American backer wrote about the frustrations of flying the drone compared with what was promised in the promotional video.

"Follow me... Hold position... Gesture control... Return to base... all claims on the Kickstarter Campaign video," he wrote.

"So, how close are they? Seems like most people are pleading with them to send one that flies... Jeez!"

Anger mounted as Torquing Group started sending Zanos to people who had paid to pre-order them before those who had backed the Kickstarter project.

That was seen as a betrayal to backers who could not get a refund. By contrast, pre-order customers were getting their money back if they cancelled.

"Sending Zanos out to pre-order customers before backers was a huge mistake in my opinion," one backer, David Black told me.

"The backers were the people that brought this project to life and should have been Torquing's priority.

"Sending to pre-orders seems to show a lack of respect to backers and Kickstarter in general."

Image copyright Kickstarter Image caption Questions are being asked about Kickstarter's own responsibilities

Some attacked Kickstarter itself, saying the crowdfunding platform should not have allowed the project to go ahead without checking that the promotional video gave a true picture of the product.

"I will never invest in a Kickstarter again," wrote Ashley Hall on a forum.

"You save a small amount of money but ultimately you end up with a partially completed beta product."

Earlier this month I contacted Reece Crowther, Torquing's marketing manager. I asked a number of questions about the project and its failure to deliver what had been promised, but received no response.

Last night, after news of Reedman's resignation emerged, I got in touch again.

This time Crowther did respond, but only to say this: "We will be releasing an official statement in the next 48 hours to address the recent resignation of Ivan Reedman. We are still digesting this news internally and we are in a state of shock at present."

So, Zano's army of backers will have to wait a while to find out what happens next.

It is safe to say that many, if not most, have already given up on what now looks like Europe's most disastrous Kickstarter project.