I would just like to point out that Henry as built was essentially a cross between an Ivatt atlantic and an A1. Basically, Henry was built from stolen A1 plans, issue was that the would be thief buggered up and stole some prototype A1 plans that Gresley had discarded. The result of all this was that in circa 1919, the engine that was built had quite a bit of resemblance to an A1, but that had bits of C1 thrown in as a sort of stop gap measure due to the flaws from the discarded plans. This engine naturally didn't work particularly well, the main issue above all else being a tiny firebox that couldn't raise steam. Eventually the first Topham Hatt, TFD, desperate for engines, made a sale for what he believed was a Robinson Atlantic. By the time Henry was delivered, and Topham found out he had been swindled, the seller had long since disappeared, leaving Topham with the white elephant that was Henry. Given how much they needed engines during the early days on the NWR, they tried all sorts of things to make Henry steam correctly, which he would with a good lot of coal. Problems were made worse when he stuck himself in the tunnel and was bricked up, the stay in the tunnel only made things worse for poor Henry, especially when a bad lot of coal came in circa 1935, which due to his tiny firebox, wouldn't make the heat. Of course, as we know, Welsh coal was brought in, and Henry's performance immediately changed to rival that of Gordon's. A few months later, as well again know, Henry was scheduled to take the Flying Kipper, things went well, Henry was running fast. But heavy snow forced the signal down, and froze points diverting him off his path. Henry nor his crew were to know and not long afterwords Henry collided at high speed into a parked goods train. Henry was badly damaged, but instead of repairing him, Topham took the opportunity to instead rebuild Henry. As such he was sent off to Crewe works, due to Topham and a certain William Stanier having a close friendship due to their time apprenticing at Swindon together, and apparently, Stanier had owed Topham a favor. The result was that in a surprisingly quick period of time, Henry was completely rebuilt into a design near identical to Stanier's Black 5s, painted NWR green, because, of course, that was the color Henry was painted in.
Now it should be noted, Henry 1, henry as built, was a pacific. the first illustrator, Dalby, is well known for his inaccuracies and inconsistencies. From the kipper incident onwards, Henry is a black 5
In the TVS, they tried to keep the differences to a minimum to make the change over after his rebuild easier, The splashers were added back because of how bare Henry's running board looked