Percy was most likely built by the Avonside Engine Company sometime around the 1900's and has gone through a subsequent rebuild in the before he was sold second-hand to the North Western Railway by a factory on the Mainland. He is said to have been found to contain Hunslet parts, among others, according to workers at Crovan's Gate.
When Gordon, James and Henry went on strike in protest of the extra work they had to do since Thomas left to run his branch line, the Fat Controller decided that the railway needed another tank engine. Going to the engine workshop, the Fat Controller saw a green saddle tank and when the engine confirmed he was willing to work hard, the Fat Controller bought him and named him Percy. Bringing him back to Sodor, Percy was charged with running the branch line while Thomas ran the Main Line with Edward and was allowed to stay after the big engines surrendered and returned to work. At first, Percy liked to annoy the big engines. Percy was later waiting at Tidmouth, but forgot to whistle to the signalman, and thus was startled when Gordon came running towards him with the express. Gordon managed to stop in time, but Percy was so frightened, he ran away and ended up stuck in a sandbank. He was rescued by Gordon and took up the duty of station pilot at Tidmouth.
Percy was still a cheeky engine and often liked to play jokes on Gordon and James, but one day the other engines got their revenge when Percy failed to recognise a "backing signal." After this, Percy was subject to bullying from the big engines until Duck arrived and helped Percy to put the big engines in their place, although Percy still received a reprimand from the Fat Controller for it.
With Duck's arrival, Percy was sent to Thomas' Branch Line to help build Knapford Harbour and has stayed there ever since as a goods engine. He met a self-centred white helicopter named Harold who said that railways were "slow and out-of-date," so he decided, to race him, of which he won. When Percy had to take the Sunday School children home, he came across a flooded paddock which swashed away his fire. Thankfully, with a little help from Harold, who had dropped supplies of hot drinks for his crew and the passengers, he was able to get the children home.
Despite being really useful, Percy was prone to having accidents, sometimes for acting naughty, and others for carelessness. He was naughty when he asked the trucks to push him past a danger notice, only to end up in the water until he could be lifted out and taken to the works by Henry. When a diesel railcar named Daisy came to look after Thomas' Branch Line, she constantly kept leaving behind the milk van every time Percy shunted it for her. Fed up with taking the milk for her, Percy offered to take Toby's trucks for him while he took the milk. However, the trucks were unfamiliar with Percy, and when he ordered them about, they decided to seek revenge by pushing him onto a line of stone trucks.
One winter, the cold was severely getting to Percy, so he tried to think about warm things. As a result, his workday led to Percy obsessing over scarves and seeing everyone around him wearing them. Henry remarked on the silliness of an engine wanting a scarf, but Percy bit back with a comment about Henry's funnel size. The cold did not affect Percy's cheekiness however, as he planned on startling the coaches by coming in quietly. However, the porters didn't hear him either, and Percy crashed into their luggage trolley, ending up covered in jam with the Fat Controller's hat on Percy's lamp iron and his best trousers wrapped around Percy's funnel. James joked that Percy found a 'scarf' after all and ran off to tell Henry. That night, Thomas and a clean Percy prepared to go to sleep happy that the firelighter had agreed to arrive earlier the next day. Henry and Percy make up, and Henry assures Percy that the weather will be warmer the following day.
In Tale of the Brave, Thomas told Percy about some mysterious footprints that he saw at the China Clay Pits. Percy convinced himself that it was be footprints of a monster that was roaming Sodor. Continuing to be anxious for a few days, he caused lots of confusion and delay such as: mistakenly referring to Gator, the new engine as the monster, failing to delivery his mail on-time and running off before The Fat Controller finished talking to him. After talking with his new friend Gator, he understood what being brave is like and later used this courage to save James from a huge landslide. He later learned that the monster was really a dinosaur a long, long time ago, which had now become a fossil. He also understood that the footprints Thomas saw, were also only fossils left from the dinosaur. Percy later said goodbye to Gator, who had to return to the mainland, but the two friends were certain they will meet again someday.
In the eighteenth season, Percy was starting to miss Gator and tried to forget him by working hard and not think about him. When he had to deliver trucks full of precious sculptures and paintings for a special exhibition, he didn't stop to be coupled and the Troublesome Trucks went rolling to the Old Mine. He thought about Gator and his advice of how to be brave. Percy goes into the mine and rescues the trucks. Percy reunited with Gator at Christmas.
In the nineteenth season, he was to take the Mayor of Sodor to the Search and Rescue Centre to present a new alarm bell to celebrate their one thousandth rescue. Diesel overheard Percy talking about it at the Docks and he played a trick on him, sending Percy to the Old Quarry which resulted him ending up on a badly flooded railway line and after Diesel unsuccessfully attempted to pull him out of the flood, he too also ended up getting stuck in the water after it badly damaged his generator. The rescue of Diesel and Percy marked the Sodor Search and Rescue Centre Crew's one thousand and first rescue. He was once giving the job of transporting Farmer McColl's ewes to a fair at Maithwaite, however he was late delivering that nights mail. Rushing to get back on time, he bashed his lifestock wagon into a flatbed, and unknowingly created a hole in it. He collected the sheep from McColl Farm, but every time he stopped some of the sheep escaped. By the time he had reached the fair, all the sheep had escaped. Fortunately, Thomas, Annie and Clarabel arrived shortly afterwards with the sheep, much to Percy's relief. Once, he saw some painters at Knapford, talking about the Fat Controller "leaving." He told Thomas and the other engines, and they came to the conclusion he was leaving Sodor because of them, so they decided to create no confusion and delay until he decided to stay. By the end of the day, it appeared their plan was successful, though Percy still had his doubts. His suspicions were seemingly confirmed when he saw the painters clearing out the Fat Controller's office. Now believing the Fat Controller was being forced to leave, the engines decided to go on strike until he was allowed to stay. After much confusion and delay, the Fat Controller explained to the engines that he was just moving to a temporary office while his was being redecorated. With the misunderstanding cleared up, Percy and the other engines worked hard to get the railway back on schedule.
In the twentieth season, he had the job of taking the Christmas Mail to Vicartown for Hiro to take to the Mainland and onwards to the North Pole. Harold offered to help, but Percy refused, determined complete the job on his own. After he left a bag of letters behind at Dryaw, Harold chased after him, but Percy, believing he was mocking his speed again, refused to stop and crashed into a snowdrift at a tunnel. Stuck, he reluctantly agreed to let Harold deliver the Mail. The following day, he heard from Toby that Harold had not returned to Sodor that night, so he raced off to the Mainland to find him. He found him stuck in a field and out of fuel. Not wanting Harold to spend Christmas stranded and alone, he fetched his fuel and the two returned to Sodor. Later, Percy was taking the Mail Train at night, when he came across the Watermill bridge and heard a moaning sound which gave him a fright. Percy later told Thomas and Toby about it, and remembering the story of The Three Billy Goats Gruff, he thought it's a troll that lives under the bridge. The three engines reluctantly crossed the bridge and discovered it was only a lost cow. He was also the only engine to be nice to Hugo, who was being shunned as the others though he had come to replace them. He would then see a Zeppelin in the sky and question how "Hugo" could be in the sky AND on the rails!
In The Great Race, Percy took Thomas' place in The Shunting Competition of The Great Railway Show after Thomas had an accident and was left on Sodor. However, Thomas managed to make it to the Mainland after all and Percy dropped out of the competition so his best friend could compete, and because he didn't want to compete in the first place.
Percy is a rather cheeky, but kind engine, and generally behaves well, except when he is getting into mishaps from being over-eager. He loves teasing the others, especially the bigger engines, such as Gordon and James, but is always brought down to earth in due course by anyone who gives him the moral to learn, especially the Fat Controller.
As the television series has progressed, Percy has been dumbed-down in order to teach viewers difficult words: he would say "dingy-fried" where anyone else would say "dignified," or make "demonstration" into "dimer-station". He is also shown to make silly mistakes, but then fix them upon realising what he has done before further damage is caused.
Although their friendship has been turbulent at times, Thomas is generally portrayed as Percy's best friend, he is also good friends with Toby as well.
Since the second season, Percy has had a small rivalry with Harold, stemming from their race. However, they are always willing to help each other when in trouble.
He also had held a grudge from the big engines about their tricking him into misinterpreting a signal, but silenced this with some help from Duck. This shows that, when nonsense goes too far, Percy will not stand for it and seek help to settle the matter for good, even if he faces a reprimanding from Sir Topham Hatt for it.
Percy is based on a hybrid of an Avonside 0-4-0ST with Hunslet underframes and valve gear, a smokebox protruding from his saddletank, external cylinders and motion, and sandboxes underneath the tanks on his footplate. He was likely built or rebuilt with leftover parts.
Modifications made to Percy's shape include the angled smokebox supports and possibly a coal bunker.
Percy is painted in the North Western Railway's green livery with red and yellow lining and the number "6" painted on his bunker sides in yellow.
In the Railway Series, he carries two builder's plates, one on either side of his cab.
The Reverend W. Awdry and C. Reginald Dalby did not get along very well. Awdry considered Dalby's drawings "toy-like;" this relationship was worsened by the creation of Percy, who was depicted as an Avonside 0-4-0ST/GWR 1340 Trojan with a bunker.
When Percy the Small Engine was published, Awdry wrote to Dalby, criticising his illustrations and claiming Percy resembled "a green caterpillar with red stripes." This was too much for Dalby and he promptly resigned. However, the insult was not forgotten: Thomas called Percy "a green caterpillar with red stripes" in Tramway Engines as well as the televised episode Woolly Bear.
It is debated as to what year Percy arrived. The Island of Sodor: Its People, History and Railways states that Percy was made the station pilot at Tidmouth in 1949, somewhat implying that he arrived on Sodor in that year. However, Henry is said to have been rebuilt in 1935 and Percy makes several appearances before Henry's overhaul. This suggests that either Henry was rebuilt later on or that Percy arrived before 1935. A post on SiF states that Christopher Awdry affirmed the arrival date in The Island of Sodor: Its People, History and Railways to be incorrect and that Percy came to Sodor before 1935.
Percy on the Big Screen
Percy was voiced by Linda Ballantyne in Thomas and the Magic Railroad. In the film, Percy arrived at Knapford with his Mail Train, he told Thomas about Mr. Conductor and conclude that he travels on Sodor to the magic railroad. Thomas told Percy about the missing truck and realised that the buffers leading to the magic railroad and told Percy to guard the buffers to be a brave engine. Later, Percy found Splatter and Dodge at the magic buffers and raced to warn Thomas, telling him to get Lily back to Muffle Mountain before Diesel 10 destroyed the magic railroad.
One of Percy's original face masks is owned by Twitter user ThomasTankMerch.
Percy went through several aesthetic changes in the television series:
Season 2 (only):
His right side piston was loose and would shake violently when moving.
His centre lamp iron was heavily glued in.
His whistle changed shape (now being more like Gordon or Henry's).
Later in the season, his whistle sound would be his own but in a whole step lower in pitch.
His two front sandboxes were flipped around.
His whistle sound changed back to its original pitch.
His smokebox was raised up.
In some episodes towards the end of the season, one of the two black sections extending from under his smokebox to the end of the footplate is missing.
Thomas and the Magic Railroad:
He gained a permanent lamp.
He gained a stand underneath his smokebox.
The lining on his pistons was moved slightly inwards.
His eyebrows change shape.
His cab was blacked out (except for cab shots filmed on a larger model).
Jack and the Sodor Construction Company (large scale model only):
The step ladders on his running board are painted red.
His whistle is taller than his cab.
His dome is painted green.
The Great Discovery:
His large scale model's dome is painted gold.
His large scale model's stepladders were painted green.
Hero of the Rails:
His cab became open again
The counterweights on his wheels vanished.
His side rods become silver.
"Do you know what?"
"Do you know what?"
"Silly! Of course I don't know what, if you don't tell me what 'what' is."
- A conversation between Percy and Gordon, "Percy the Small Engine"
"Wheeeeeeeeeeesh! Don't be frightened, Thomas, it's only me!"
"Your ugly fizz is enough to frighten anyone, you're like..."
"Ugly indeed! I'm..."
"A green caterpillar with red stripes. You crawl like one too."
"Who's been late every afternoon this week?"
"It's the hay."
"I can't help that! Time's time, and the Fat Controller relies on me to keep it. I can't if you crawl in the hay 'till all hours."
- An argument between Percy and Thomas, "Tramway Engines"
"Harold told me you were a ..... uh, wizard. He says he could beat you at some things but not at being a submarine. I don't know what you two get up to sometimes but I do know you are a really useful engine."