- "If anyone needs me, I'll be laying low in a tunnel for awhile."
- ―Luke, "All the World's a Stage"
Luke is a plucky-green Irish engine. He came to the Island of Sodor, which was a dream of his for a long time. He was lifted onto a large cargo ship, and was very excited. A Spanish-speaking yellow engine who had ridden the boat all the way from Cuba was there when he came on. During the trip, a storm raged, breaking the chains holding the engine down to the boat. Luke was unaware of this development. After weeks or possibly even months, Luke and the yellow engine arrived at Sodor. The workmen were originally going to lift the yellow engine onto land as soon as they arrived, but Luke wanted to be the first off the boat. The workmen agreed, but when Luke was lifted up, he bumped into the yellow engine and he fell into the sea. Luke, ridden with guilt, thinking he had caused the engine to be scrapped, ran away and hid in the Blue Mountain Quarry.
A few years later, Paxton had an accident at the Blue Mountain Quarry, and Thomas was marshalled to do his work. Thomas saw Luke, and asked the other engines about him. They pretended to know nothing, but eventually revelaed that they were protecting him from being sent away from Sodor forever. He soon got close to him, and Luke told Thomas the story. Thomas did some investigating, and found out Victor was this engine.
Thomas told the engines that he found out that the yellow engine wasn't scrapped, but Luke and the other narrow gauge engines misinterpreted the situation, and thought Thomas had turned his back on them, and told Victor about Luke's secrets. Feeling betrayed, they all puffed away from Thomas. Determined, Thomas asked Rocky to lift him onto Owen and carry him up to the upper terrace. Thomas, being too big for narrow gauge rails, rolled out of control onto the edge of a cliff. Luke, realizing that he is the only engine that could rescue Thomas, pulled him to safety. The truth was soon revealed, and Luke and Victor are now on good terms! Now, Luke enjoys his new life on the Island of Sodor, and is thankful he no longer has to hide away in the Blue Mountain Quarry.
Later, Luke encountered a fawn in the quarry and befriended it, though this proved difficult due to the industrial work at the quarry. Skarloey suggested that Luke deliver some gravel to Ulfstead Castle and take the fawn there, whereupon it was reunited with its mother.
During another occasion, when Luke had to make a slate delivery to Ulfstead Castle, he encountered Millie, Sir Robert Norramby's private engine. The two had an argument about their respective jobs, and Luke then suggested that they switch to see what it was like to do the other's work. Norramby thought the idea was interesting, and when he told The Thin Controller of this, the latter agreed. Luke then found out that Millie's job was a tad slower than his, as he had to go slowly in order to give people a decent tour, and in order to locate certain areas of the estate. At the end of the day, both he and Millie agreed that while it was fun to do another's work for a change, they would stick to their respective jobs in the end. He has been seen with Millie frequently, like their adventure at the Blue Mountain Quarry.
Also, when Stephen came to the Blue Mountain Quarry, Luke warned him to go slow on the corners but it was too late. Stephen jammed on his brakes and he tipped over.
Later, when the Skarloey Railway was forced to put on a production of Hamlet, shy little Luke decided it would be best to lie low for a while and headed for the nearest tunnel, thus allowing him to avoid taking a role in the play. Unfortunately, his fellow engines were all frustrated when they found out that he had managed to pass by the horrendous experience, while they suffered under Bertram's directing.
Luke is a meek, enthusiastic, and hard-working young engine. He can be a little shy, which causes the other engines to be very protective of him. Luke is slow to make friends, but builds a very strong bond with them when time has passed and trust has formed. He loves working in the Blue Mountain Quarry, and is very passionate about his work. To this day, you'll often hear him chortiling with joy as he races along the terraces of the Quarry.
- Season 2: Blunderbuss (cameo), Swan Dive (cameo), Luke and Millie's Blue Mountain Adventure, Aura of Menace (cameo), Henry and Kurt (cameo), All the World's a Stage, Swashbuckler (does not speak)
- Season 3: Logan Leaves his Mark (cameo), Chivalry is Dead (cameo), Percy and Asbestos (cameo)