It was announced last September that UK chip designer ARM was being taken over by US giant Nvidia.

But the deal was subject to regulatory approval and now the UK Government has decided to intervene on the grounds of national security - although it is unclear as to what "national security issues" there could be given that the company has been owned outright by a Japanese firm for the last four years. Like Softbank, Nvidia is a public company. 

"As a next step and to help me gather the relevant information, the UK’s independent competition authority will now prepare a report on the implications of the transaction, which will help inform any further decisions" said UK Digital Minister Oliver Dowden, who has issued an intervention notice ahead of the probe. 

Our original story continues below: 

Legendary British chip designer ARM is being bought by Nvidia subject to government and regulatory approval.

Nvidia currently designs chips based around ARM's technology, in addition to its hugely successful graphics business and other efforts in autonomous vehicles and more. 

ARM has grown from the days of its Advanced RISC Machine processor inside the BBC and Acorn machines of the 80s into one of the biggest technology companies in the world. It is based in Cambridge, UK.

Its technology - which it licenses to other manufacturers, such as Apple, Samsung and Qualcomm - is used in around 95 per cent of smartphones and tablets and will be used more in PCs as Apple launches its own processors for the Mac and in Windows PCs using Qualcomm processors

After becoming a public company, it is largely owned by Japan's SoftBank. However, Nvidia has pounced in a deal worth $40 billion.

Whether it will be approved is a subject for debate. And, of course, there is potential for ARM's technology to be more permanently withheld from Chinese companies as part of the US-China trade war. 

Nvdia says it is committed to keeping ARM's business in the UK, which makes sense given the amount of technical expertise in and around the company's Cambridge base. But, it'll be interesting to see how this plays out over time with the end of the Brexit transition period on the horizon.

The company's founder, Hermann Hauser, suggested on the Today programme on Radio 4 that the move is "an absolute disaster for Cambridge, the UK and Europe".

"If hundreds of UK companies that incorporate ARM [tech] in their products want to sell it and export it anywhere in the world including China - which is a major market - the decision on whether they will be allowed to export it will be made in the White House and not in Downing Street," he said.

Nvidia, though, is understandably more bullish and positive: "ARM’s headquarters will remain in Cambridge and continue to be a cornerstone of the UK technology ecosystem. Nvdia will retain the name and strong brand identity of ARM," said Nvdia's founder and CEO Jensen Huang in a statement.

"ARM gives us the critical mass to invest in the UK. We will build a world-class AI research center in Cambridge.

"Uniting Nvdia's AI computing with the vast reach of ARM's CPU, we will engage the giant AI opportunity ahead and advance computing from the cloud, smartphones, PCs, self-driving cars, robotics, 5G and IoT."

Ironically, SoftBank also previously owned a stake in Nvidia, which it sold in 2019.