And it was the work of accomplished pilot, engineering genius and effective salesman Harry Ferguson that made the modern day farm tool what it is.

A new documentary on BBC ALBA – entitled 'Am Fergie Beag Glas' (The Wee Grey Fergie) explores Ferguson's achievements in the company of some of the many farmers and enthusiasts who will not let his name be forgotten.

Indeed, Ferguson is so revered in his native Northern Ireland that his face now graces their £20.

In the programme, viewers get a glimpse of the vast Ferguson collection held by crofter Donald A MacLeod in Lochgilphead.

Donald, who was originally from the Isle of Skye, sadly died last year aged 72, but his close friend Allan Campbell, who presents and narrates 'Am Fergie Beag Glas', says that Donald always wanted to see Ferguson's story told.

Allan said: "Donald Macleod collected them because he appreciated this tractor's history.

"Looking at Harry Ferguson's life and engineering, he saw something with a lasting effect and which improved the farmer's life. I think it was the extent of his dream (Ferguson), which left Donald captivated by this man."

Born in 1884 in Dromore, Co Down, fourth of eleventh children, Harry Ferguson began his career mending bicycles in his brother's garage.

Within a few years he had developed a hydraulic system that united tractor and plough in one unit, giving depth control and lift at the touch of a lever.

Not only did this revolutionise ploughing it also ended the age-old problem of ploughs constantly getting caught on stones and boulders which at times had terrible consequences, causing tractors to topple over, injuring and sometimes even killing their driver.

By 1939, Ferguson's determination gained him a manufacturing deal in the US with world-renowned motor giant Henry Ford, and by the 1970s Ferguson's system was used in 80% of tractors world-wide.

Though Ferguson had many inventions, his last tractor, the TE20 – better known as the Wee Grey Fergie – is perhaps the best remembered.

Donald Meek, from Tiree, recalls how his Dad got a Ferguson TE20 in 1946 and everyone wanted their photograph taken with it.

"It was very special. I was an iron horse, friendly and loyal," he said.

And Cailean MacDonald, from Inverness, also recalls the model with fond memories: "I took out tractor to dances in Carloway when I was about 17," he said.

"I offered a girl a lift home but she though I had a car! When I came out, I put on my yellow whaler's oilskins but she wasn't willing to go home with me at all that night.

"I took her home since then though." he added.

70 years on The Wee Grey Fergie is still working reliably and is very much loved.

'Am Fergie Beag Glas' can be seen on BBC ALBA, Monday February 8 at 9pm.