In 1940, a small, bespectacled, eccentric English artist was sent to paint the Clydeside shipyards and the men who worked there - and a small, tough, 20-year-old welder on £2.50 a week was told to help him.

The artist was Sir Stanley Spencer who went on to create the extraordinary series of paintings known as Shipbuilding on the Clyde, two of which are on display at the Riverside Museum in Glasgow. The welder was John Dodds who, 70 years after his association with Sir Stanley, has been tracked down for a new documentary.

Dodds is now 92 and lives not far from the site of the Lithgows yard in Port Glasgow where he worked in 1940. In the documentary, to be shown on BBC2 tomorrow, Dodds relates how he first came to meet Sir Stanley and the conditions in which the famous works came to be painted.

According to Dodds, the painter was a slightly dishevelled figure but extremely hard-working. Conditions in the yard were not easy but the artist would stand sketching in the cold and wet from morning til night. He was apparently nervous about going to the yards but fitted in extremely well. "I like it here," Spencer said at the time, "being lost in a jungle of human beings, a rabbit in a vast rabbit warren."

"He fitted in," says Dodds. "He was such a quiet man and his approach to everything was consideration at all times. All the men that worked in shipyards felt a fondness for him - they felt that he was on his own so they would make a point of helping him at all times and show him how to avoid any chance of getting injured."

Dodds, who was a foreman at Lithgows, was told to take care of Spencer after the painter was sent to the yard by the War Artists' Advisory Committee. His mission was to depict the teams of men who were building ships for the war effort - the yard built the greatest number of merchant ships during the war.

In the end, the artist stayed for six years and Dodds was impressed with the work he produced. "He changed things round, and put curves on to things, but he did well at capturing the mood at the place. I didn't realise until many years afterwards just how good he was. His sketching was out of this world and there's one in particular I love. It includes Frank Chalmers , who was known as The Furnace Man, and he was loved by us all. Frank would let you sit on the coals to dry out if you got wet. Stanley found that when the cold overcame him, he would go to Frank."

Dodds added that Spencer would often become so engrossed in his work that he would stand in the wet in an old pair of shoes so one of the men found him a pair of boots. The shipyard workers also seemed to feel a sense of responsibility for him; they were fond of him and took him to parties.

The artist Lachlan Goudie, the presenter of the new documentary, Stanley Spencer: The Colours of the Clyde, says Spencer very quickly became inspired by what he saw on the Clyde. "He was nervous when he came to Port Glasgow," says Goudie. "He didn't know what was going to happen but when he got there and became involved in that close-knit community, he began to feel at ease and at home and felt inspired. He was also a tough guy despite his eccentricities; he had fought in the First World War and could communicate with the men working in the yards."

However, there were some things Spencer did not reflect in his sweeping, complicated pictures, says Goudie. "There's no sense that many of the ships that these men are building are doing to be sunk within months - that happened to a large proportion of the ships built in Port Glasgow. He doesn't refer to the Blitz either.

"There's a sense that these paintings could have been painted outside of war but why I love them so much is because, as war paintings, they are unique - they seem to paint the very thing that people were fighting for.

"They were fighting to defend their communities, their freedom, their ability to go to work and live amongst their friends and family - the paintings represent those values."