A retro games console crowdfunding campaign is to lose the right to feature the brands of the original computers it is based on.

The revelation coincides with the delivery of some units of the Sinclair ZX Spectrum Vega+ to backers, albeit without most of the games originally promised to be pre-installed.

Rights-owner Sky told the BBC there had been repeated missed deadlines.

It is pulling use of the "ZX Spectrum" and "Sinclair" trademarks as a result.

The decision was taken in May.

Sky has told campaign manager Retro Computers Ltd (RCL) that a licence to use the names will therefore expire on 7 August.

"We would love to see the Vega+ consoles in the hands of fans.

"However, as RCL have repeatedly failed to deliver and breached the terms of their licence, we have made the decision to end our working relationship," a spokesman for the broadcaster explained.

"To give as many gaming fans as possible the chance to get their Vega+ console, RCL [had] three additional months from termination to deliver the products."

RCL declined to comment on the allegations but said deliveries had begun last week.

Retro Computers has also sold copies of the Vega+ via its own website

"We have managed to start shipping at last," RCL's chairman David Levy told the BBC.

"But this time we did not say exactly when this would happen, so those who have thrown various spanners in the works in the past, in order to hamper our efforts, were not able this time to prevent us from shipping."

Software and name

Sky owns the intellectual property involved as a consequence of its purchase of Amstrad, which had earlier acquired Sinclair's marketing and merchandising rights. It had originally allowed RCL to use the trade marks without charging a royalties payment.

In addition to the brand names, Sky also owns the rights to a number of Spectrum games that it now intends to withhold.

Sky does not, however, have a connection to the emulation software, so RCL could theoretically continue to produce the handheld console under a different name.

The disclosure comes ahead of a crunch shareholders meeting scheduled for Thursday.

Two former directors of RCL - with a combined 50% stake - are seeking to displace the current management.

But to succeed they would need the support of Sinclair Research - the original ZX Spectrum inventor Sir Clive Sinclair's company - which owns 25% of RCL.

The crowdfunding campaign quoted Sir Clive as saying he had planned the machine to be a "handy games console"

Running late

The campaign to make the handheld console was launched in February 2016 and went on to raise more than £512,000.

Backers were originally told deliveries would be made in September of the same year and 1,000 licensed games would be included.

After several missed delivery targets, the company sent out the first units at the end of last week.

It has said it is in the process of shipping consoles to 400 of the more than 4,000 backers, who had agreed to receive units with only a small number of games. Nineteen titles appear to have been included.

To date, a handful of people have confirmed receipt of the devices, via social media posts, several of whom have complained about the quality of the console.

"The buttons are absolutely awful," wrote David Whitchurch-Bennett.

"You have to press so hard and they intermittently stop working unless you apply so much pressure."

Craig Wootton complained his console had arrived with "no protection, no bubble wrap, polystyrene et cetera".

"The screen cover itself is scratched," he added in a video posted to YouTube. "That's pretty poor, if I'm honest."

He also said that a lack of instructions had left him at a loss as to how to add other games.

RCL director Suzanne Martin has posted on Facebook that the machines had been deliberately "shipped in ethical packaging without any additional plastic" and that information about how to use the consoles would be made available online.

One recipient has been more positive.

Jan Saggiori has posted several messages on social media saying how much he has enjoyed playing the console.

He had earlier been blocked from making edits to a Wikipedia page dedicated to the Vega+ over claims he was affiliated with the project and therefore biased.

But he told the BBC that this was a false allegation and his involvement was limited to running an independent Facebook group dedicated to supporting the project.

"I am a backer who upset the trolls [and] have no affiliation to RCL," he said.

"I have been personally targeted... and attacked, threatened, blackmailed for supporting the campaign."

Indiegogo - the crowdfunding site that hosts the project - announced in June that it had appointed a debt collection agency in an attempt to recoup backers' funds.

The BBC understands the US company is still pursuing collections despite the fact some deliveries have been made.