Henry was built using plans stolen from Sir Nigel Gresley around 1919. The prototype turned out to be something of a cross between a GNR/LNER Class A1 and a GNR C1 Atlantic. Although the design was a failure, Henry was sold in 1922 to Sir Topham Hatt, who was desperate for a locomotive.
Henry was vain and stopped in a tunnel and refused to come out, citing that his paintwork would be spoilt by the rain. After several attempts to move him failed, he was bricked up in the tunnel until Gordon broke down while pulling the Express. As Edward was unable to move the train himself, the Fat Director offered to let Henry out of the tunnel to help. Henry eagerly accepted.
Henry performed very well, and the Fat Director promised him a new coat of paint, since Henry's existing paintwork had been spoiled more by his stay in the tunnel than it would have been by the rain. Henry asked to be painted blue like Edward. However, many people confused him with Gordon, to the bigger engine's annoyance. The matter was worsened after a trip to the Works when Henry was given spares of Gordon's buffers. Sometime before 1935, Henry, when again offered new paint, chose green and so ended the Gordon/Henry confusion.
Unfortunately, Henry was to suffer humiliation when he was hosed with water by an elephant he frightened. After Gordon and James had suffered humiliations of their own (and all three had become thoroughly fed up having to do their own shunting and fetch their own coaches), the big engines went on strike. The Fat Controller naturally disapproved of this nonsense and locked them in the shed for several days. However, they were let out again after promising to work hard.
The poor engine and his system, which was already finicky at best due to design flaws, never really recovered from his stay in the tunnel. Henry developed steaming problems, which he complained constantly about, though he found little sympathy, especially when it caused him to run late.
A period came when the Main Line engines were supplied with a poor delivery of coal and Henry had a very difficult time of it indeed. He had strength to pull trains only sporadically, in spite of numerous parts replacements. At last the Fat Controller looked into it personally, and asked the opinion of Henry's fireman, who told him about the poor coal and Henry's firebox being too small to burn it efficiently. The fireman also suggested purchasing the high-grade Welsh coal used on the Great Western Railway. Sir Topham Hatt agreed to purchasing some in order to give Henry "a fair chance".
When the Welsh coal came, Henry's performance vastly improved, such that he was comparable to Gordon. He continued to use the coal until he had a collision with a goods train at Killdane while pulling "The Flying Kipper" and was sent to Crewe to be rebuilt in 1935. Henry was rebuilt into a Stanier 5MT. (Sir Topham Hatt had connections with Sir William Stanier, so this may be the reason he managed to get Henry rebuilt so quickly).
After returning, Henry was added to the rotation for the Express, and pulled it so well that he made Gordon jealous. Gordon tried to get even by rudely criticising Henry for whistling loudly at stations, but had to eat his words later that day after his own whistle valve jammed open. Some time later, Henry was taking a slow train. As he passed under a bridge, four boys he had assumed to be railfans dropped stones on him and his coaches. He paid them out on his return journey by "sneezing" ashes that collected in his smokebox at them.
When Queen Elizabeth II was due to visit Sodor in 1953, Henry (justifiably) assumed that he was the Fat Controller's choice to pull the Royal Train. But the day before, while he was idling at the station his smoke blinded a painter, who fell along with his paint pot onto Henry. The paint splashed over Henry's boiler, and as painting over it would take too long, Gordon was given the job instead.
When Duck arrived in 1955 to take over Percy's duties as station pilot, Henry, along with Gordon and James, teased him and tried to give him orders, as they had been doing to Percy. Duck, with Percy's help, blocked the big engines from entering the shed. The Fat Controller arrived and told the two tank engines off for causing a disturbance. Henry and the others laughed- until the Fat Controller shouted for silence, and told them they had been worse, as they had made the disturbance. He told them that Duck was right - he, Sir Topham Hatt, is in charge. Henry respected Duck more after that.
Henry's good opinion of Duck would be briefly spoilt in 1957. He and the other main line engines were growing very tired of Duck's incessant talk about the Great Western Railway following City of Truro's visit. A Diesel sent to the island on trial quickly developed a grudge against Duck, and spread nasty stories about the main line engines to the trucks, stories he falsely claimed Duck had told him. Henry, furious at being called "Old Square Wheels", joined Gordon and James in barring Duck from the shed. He felt sorry a few days later when he became the next target of Diesel's slander, and when Duck returned after preventing an accident Henry cheered for him loudly.
When Gordon started feeling depressed in 1967, Henry, thinking Gordon was just moaning and groaning, teased him and told him he should get a wash-out, and would feel much better. When Gordon's brother Flying Scotsman visited Sodor, Henry was jealous of the visitor's second tender. Duck and Donald explained, and while Henry took the point he still was vain enough to want an additional tender. Duck, deciding to bring Henry down to earth, told the big engine that he had in his possession not one, but six spare tenders, which, as a tank engine, he had no need of. Henry accepted, and all the engines waited to see him go past. But instead of a splendid sight, the tenders were old, rusted, and full of boiler sludge! Gordon mocked him with a comment about wash-outs.
Henry was so frustrated that the day after 7101 and 199 arrived on trial he became so hot his regulator fused wide open, and his driver had to use the reverser to control him. On his return journey (no train), he stopped at a signal box next to 199, who had a train of oil tankers. The signalman told them that 199, who he nicknamed "Spamcan", had failed and that he needed to be moved out of the way to clear the line for the "Limited". Henry pulled the train clear. But shortly afterward, 7101's ejector failed and the "Limited" ground to a halt. Henry then volunteered to help move both trains. Luckily all he had to do for 7101 was keep the vacuum brakes off, but it was still hard work. The cavalcade made it to a station where Flying Scotsman waited to take the coaches, and Donald to take the goods. Henry brought 7101 to the Works afterwards and days later cheered the arrival of Oliver.
Later, when Gordon needed new tubes, Henry pulled the express, but soon fell ill as well. This left the job of the express to Thomas, Percy, and Duck. A while later, Henry had to pull an extra long Flying Kipper and Duck had to help him up Gordon's Hill, but due to a tail-lamp falling off the rear van, Duck accidentally crashed into the brakevan.
Henry also had a problem with his fire after disagreeing with James on the colour of red paint, but said nothing more after the event.
Henry then complained to Thomas the time that the Viaduct had gone under repairs, when Thomas became impatient with his connection between the main line engines and his branchline. Henry also had a late start a few times when Thomas had run away and when he had a leak in his piston rods.
When Gordon accidentally blew ashes when his smokebox was clogged, Henry suggested that Gordon have a good "sneeze", but Gordon reminded Henry that The Fat Controller didn't like Henry's sneeze. He also pulled the express when Gordon slipped on the icy rails and befriended Pip and Emma.
When Thomas had been invited to the Great Railway Show, he was angry that he wasn't chosen, and later teased Percy that Thomas was old enough to become a museum piece.
Unfortunately for Henry, he had to go back to the Works for an overhaul. He had many problems and even had an overcoat of red paint on him! The other engines did Henry's jobs (including pulling the Flying Kipper) while he was away.
He later fretted over the Golden Jubilee despite Duck, Daisy, James, and Donald trying to cheer him up.
In the TV series, Henry loved visiting the forest. Due to his love of the forest, he has helped to replant trees after a storm destroyed the forest and later helped the workmen prune the trees that were getting too close to the line.
He also has had to go back to the Works on several occasions, such as when his tubes were leaking and after he had an accident with some trucks. But the reason most often given for Henry's poor state is that he needs special coal again, even though this was corrected in the first season. This error has been fixed as of King of the Railway as Toby states that the fact that Henry needed special coal was fixed years ago.
In the eighteenth season, Henry was scared by the Flatbeds of Fear when taking a load of pipes to a building site. He was so scared that he could no longer pull the flatbeds and Emily had to take them for him.
Henry is generally well-behaved, but he is occasionally arrogant and vain. Henry is at heart a hard worker, but his frequent bouts of illness hinder his work. His illness almost always involves his boiler having some sort of issue.
In the television series, Henry has been portrayed as a nature-lover as evidenced in Henry's Forest. This personality carried on throughout the more recent seasons with Henry being occasionally a tree-hugging engine too as he tried to prevent the tall pine tree and the wishing tree from being cut down.
In the newer seasons, Henry is portrayed as not too bright, and sometimes really worrisome, as shown in multiple episodes.