The 1927 footage, on a phonovision shellac disc, is the world's oldest surviving 78rpm piece of video.

It features Baird's ventriloquist dummy Stookie Bill, which he used when developing his invention.

The recording will now be stored at the University of Glasgow.

It was part of a collection which was made subject to an export bar in April, following fears the collection would be sold abroad.

The collection, which also includes the log books used by Benjamin Clapp while conducting Baird’s transatlantic television trials and the world’s first known use of the acronym TV, was put up for sale in April 2015 and looked almost certain to go to a private collector overseas.

But a temporary export bar was placed on its sale until Tuesday (today), and the University of Glasgow can now confirm it is currently in the process of buying the collection.

The businessman who has funded the purchase wishes to remain anonymous, but he lived in Helensburgh - Baird's hometown - for 20 years.

He said: “I am delighted the collection has been saved and is now coming home. It charts such an important period of modern engineering history so I felt it could not, and should not, leave these shores to move abroad.

“It needs to be shared for future generations.

“John Logie Baird was a Helensburgh man and a Scottish pioneer who helped change the world, and with his ties to the University of Glasgow I think it is only right and proper that this important collection should be coming to the university and hopefully it will help inspire future pioneering engineers.” The items will be an important addition to the university’s John Logie Baird archives.

Baird was a student at the University of Glasgow from 1914-1915 where he studied engineering. He cut short his studies when he tried to voluntarily sign up for war duties in 1915, but was turned down on health grounds.

Professor Anton Muscatelli, Principal of the University of Glasgow, said: “I am delighted that this important, historical collection will be coming to the University, greatly enriching the collection already owned by the University.

“We’re proud of the fact that John Logie Baird is an alumnus of the University of Glasgow and so it is fitting and immensely exciting that these important items, which catalogue the world changing work he was conducting at the time of his engineering break through, are preserved here in Scotland and at the university where he studied.”