AN EXPORT ban runs out today on a precious archive detailing John Logie Baird’s triumph in achieving the first transatlantic TV transmission in 1928.

Behind this lies a thrilling tale of a secret mission to New York in the roaring twenties of prohibition and speakeasies.

We’ll know soon if the collection could now be sold overseas or “saved for the nation”, as England’s Culture Minister Ed Vaizey urged.

That could mean it remains in England. Will there be a Scottish bid? Will anyone in Baird’s homeland pay £78,758 to save a treasure trove of TV history that would attract tourists and media historians? No bidders are known so far.

Baird, transmitting from London to a handful of secret helpers in New York, was pitted against hundreds of American engineers racing to be first across the Atlantic.

Compiled by Ben Clapp, Baird’s first chief engineer, the archive contains Clapp's diaries of the quest and technicalities, plus Baird’s 1927 “phonograph” disc, the forerunner of the whole video industry.

I know this collection because in 1988 I produced a BBC Scotland/BBC 2 documentary on Baird’s story, interviewing Clapp when he was a tack-sharp 93.

By 1928, JLB and Clapp had already achieved the first transmission over 400 miles – London to Glasgow’s Central Hotel. But stretching to 3,400 Atlantic miles was still a dream.

Clapp told me: “Some reckoned that America had 1,000 engineers on the race to be first. We had about six between the US and London.”

Here’s how the adventure began: “Baird wandered into the lab in London one morning and said to me: ‘Mr Clapp, can you go to America tomorrow?’

“When I tell you we had to build the televisor to take with me, book a passage and make all the arrangements, I did fairly well by going in a week’s time”.

This had to be a clandestine mission. Clapp smuggled in his gear, calling it radio equipment as America was on red alert for TV rivals and it might have been confiscated. He arrived on a Cunarder as prohibition raged.

“As the ship docked, I witnessed the ugliest sight of my life: Customs smashing bottles of whisky against the sides of liners. But getting a drink was easy.” Clapp chuckled. “ I’d been tipped to speak to any NY traffic cop with an Irish accent. I was immediately directed to a speakeasy!”

The high drama of that first transatlantic broadcast seemed to filter into making a documentary involving it 60 years later. I had my own secret mission: to refute BBC London’s denial of Baird’s genius.

I traced a dozen former Baird men and other witnesses who, unlike their frail boss, survived to great age. But the lone US radio ham Robert Hart who, with Clapp, received the historic Transatlantic transmission in the basement of Hart’s home just outside NY, was missing.

He had disappeared after 1928, presumed long dead. I searched endlessly, and in desperation phoned NYPD.

Crashing noises exploded down the line and a cop shouted: “Hear that noise, ma’am? These are gunshots. This station is under fire from hoodlums and you’re asking about some guy who lived around here in 1928?”

I gasped apologies and the cop yelled: “Gotta go! Do what we do – go to last known address!”? A few days later, I was on a stateside doorstep at “last known address” from 1928, hoping only to trace Hart’s family.

“Come in,” said the old man at the door. “I’m Robert Hart.”

Like Clapp, he was over 90. He showed me the basement where he’d waited with Clapp for a flickering sign from London.

“The more I thought about it, the more wonderful it was. This thing in a wooden box in my basement was making history.”

American newspapers had clunky banner headlines such as: “Television traverses the Atlantic! We see people moving around in London.”

But America praised generously – UK media support was poor. Perhaps icy influence had dripped down from the BBC’s old Wuthering Heights, John Reith, Baird’s adversary from their student days in Glasgow. Reith once compared TV to the spread of the Black Death. (Did he foresee The X Factor and Jerry Springer?)

On Clapp's passage home on the Cunarder Berengaria, another first was won: TV reception in mid ocean. Ben recalled: “Some of the sailors were superstitious, thinking the images were supernatural.”

But Cunard was proud of the achievement being on their Berengaria. They freely offered to reunite Clapp and Hart, returning Clapp to NY in style, 60 years on. Hart was waiting at the quayside, and New York feted the two nonagenarians.

American radio station owner Donald Flamm, who had known Baird, called him: “A true genius, a fine Scotsman; people should be proud of the fact that one of their countrymen discovered and invented television.”

Clapp told me angrily: “What Britain did in never honouring Baird was a disgrace.”

Downplaying Baird still infected the BBC in London in 1988 (BBC Scotland was fine). I was called into a mandarin’s office at Television Centre to be propagandised that Baird was just a showman. Oh yes? Many tried for TV, but Baird was first to produce images. He registered 177 patents, demonstrated black and white in 1926 and mechanical colour in 1928 and invented outside broadcasts in the 1930s (for the BBC).

Baird gave the world its greatest communications tool. He died poor. For once, I kept quiet as this sneering executive droned on. Outside his office, I raised a one-finger salute before setting out to record the last testaments to Baird’s genius by the engineers who revered him.

Ben Clapp’s archive is further proof and must not be sold off to just anyone. All first-hand witnesses are now dead, but thankfully they recorded the truth about the man who conquered the Atlantic.