This is going around on twitter so let's try it here
Feel free to send an ask if you want an elaboration on any of these.
1. Thomas/Cassandra as a J72 is long established lore. But something never said is the fact they dont know what they are until the preservation era. As far as Thomas/Cassandra knew, they were an LBSCR E2.
2. British Railways had a secret program from the 60s to the early 80s where they would allow groups to buy engines for preservation, but only if they agreed to keep the engine's survival secret. This was to make the engines/classes seem rarer than they were and driver up their price.
3. Blue Peter was originally male, but after the 1994 Durham wheelship accident and the emergency repairs carried out at Crovan's Gate, Blue Peter reawoke as female.
4. The world is a little bit larger in the AU, with more passengers and freight. This means more members of existing classes like the LNER Raven A2 and Gresley P1, and some classes that weren't built in ours like the GWR Cathedrals and Stone Circle Class.
5. Preservation is a larger movement, due to the engines being alive. There are more preservation railways, and those that exist in our world are better funded, and often larger.
6. It is now possible to circle the island by rail, via the Mantauo line which runs North from Vicarstown to Mantauo, and the Little Western, which extends North from Harwich to Mantauo.
7. Both Stanley and Smudger exist. Smudger, offically named Jennings, was the original No.2 of the Mid-Sodor Railway. She was eventaully sold to the Cronk and Harwick, with Stanley being bought to replace her.
8. Yes Nicole and Samantha are together, and adopted Claire
9. Many 'extinct' classes of British Locomotive have surviving members in other countries. Most commonly in the Americas and Asia, but British Railways refugees can be found in most countries.
10. Flying Scotsman has been part owned by the NWR since the American Tour, which they funded the latter half of in turn for majority ownership. Alan Peglar readily agreed, as it meant Scotsman was secured no matter what happened to him. In the present day the other portion is owned by the NRM.
11. With the greater interest in preservation and the existence of Crovan's Gate, many new builds were finished earlier. For example Lady of Legend was completed in 1975. Tornado is notable in the Au for being the first standard gauge steam engine built entirely on mainland Britain since Evening Star, as all the others had Crovan's Gate built components.
12. With the extension to Mantauo, the "Little" Western is a full fledged mainline, sporting many GWR Locomotives including Castles, Stars, and Cathedrals. Despite this, all agree Duck is still the head of the line.
13. Thomas/Cassandra and Duck started dating during the Summer of 1976 while the No.1 was on the Little Western due to storm damage on the Ffarquhar Branch.
14. While LNER P2s were transferred to Sodor during the war, and remained on the island afterwards, they were rebuilt in a manner similar to Gordon and so are considered P2/1s by Railfans. The 2007 Prince of Wales new build is intended to bring back the Gresley condition design, and the P2/1s are all excited to meet their new sister (they all insist it will be a girl, and engines are almost always right about such things).
15. The LNER U1 Typhoon and Big Emma (Big Bertha) work together on the Mantauo line and are shedmates...They're also girlfriends.
16. There were plans to rebuild Henry into a Hudson before the Flying Kipper accident, but the damage he stained was great enough Hatt used a favor Stanier owed him to have Crewe repair and rebuild Henry. As his trailing axle had been destroyed in the accident, Stanier had him rebuilt as a Black 5
17. The Sodor engines take great offense to the "Two Henry's Theory" and more than one pushy railfan has got blasted with a face full of steam over it.
18. Nancy Rushen is now the Thin Controller of the Skarloey Railway.
19. The NWR fleet list is over 100 hundred engines long, despite only containing engines that have appeared in either stories or art.
20. Midlothian is safe and sound on Sodor, although she refuses to set one wheel on the mainland.
21. U.S.S. Enteprise CV-6 is in service with the US Coast Guard as a Helicopter Carrier.
22. LNER 10000 "Hush Hush" does survive, but in her rebuilt form and her name is British Enterprise.
23. All the of the engines from the Fifteen Guinea Special survive, as 44781 Excelsior was saved by the Sodor Railway Musuem when the original preservation attempt fell through.
24. Excelsior joined her sister 45318 Intrepid, who the museum had already preserved, as she had pulled the last regular timetabled steam hauled service on British Railways.
25. HMS Hood survives the Second World War, and remains in service until after the Falklands War. She is now a museum ship.
26. All three Olympic Class would survive to enter Sodor Star Line Service in 1935 (Titanic having forced herself into a turn a second earlier), sold off by White Star Line as a final act of Defiance in the face of their impending forced merger with Cunard.
27. When the American Ocean Liner SS Moro Castle caught fire in September 1934, a White Star Liner recieved her distress calls and came to her aid. R.M.S. Titanic had been leaving New York Harbor when the sos was recieved and immedaitly turned to assist. Her crew helped the Moro Castle's contain the blaze and evacuate the passengers, before towing the stricken vessel to safe harbor.
28. America has had locomotive and sentient machine rights on paper since the 1890s, but it only truly came into effect following the first world war.
29. After the second World War ended up aligning themselves with either the USA or USSR. The USSR, like the USA also had rights for sentient machines. Never content to let the other take the lead in anything, the two superpowers pushed for their allies to take similar measures, leading to most nations steam fleets being protected by the time they were economically capable of replacing them.
30. The exception for Sentient machine rights is Great Britain. Even by the 2020s, the British Government doesn't recognize sentient machines as anything more than beasts of burden, if even that. This has led to political tension between Britain and both the USA and USSR.
31. As a result of the larger world/passenger numbers, the White Star Line planned a fourth Olympic Class. Tentatively named R.M.S. Gigantic, the hull was still early in construction when WW1 broke out. The Royal Navy claimed the unfinished hull, planning to finish the ship as a troop ship, but Germany caught wind of the project, and the unfinished hull was bombed on the slipway by a German Zeppelin. The hull was a total loss, and the White Star Line cancelled the project. After the war, the Line would eventually receive the newly completed S.S. Bismark as war reparations in 1922, renaming her R.M.S. Majestic.
32. As the Titanic Disaster never unfolded, with the liner instead surviving her maiden voyage, J Bruce Ismay would remain the managing director of the White Star Line until its merger with Cunard in 1935.
33. In the United States, roads never took over like they did in our timeline. The Railroads pushed for cars to have the same rights as their engines. While seemingly benigh, this place cars outside the budget of all but the rich. Roads certainly still exist, but are primarily for emergency services and for transporting freight in areas where railroads are impractical for one reason or another.
34. Since R.M.S. Titanic survived, why did the rules and regulations following the disastestill occur. Two reasons, 1. I play by the rule of the elastic timeline. While Context may change, most global events (or at the very least their consequences) still play out. 2. The Liners went on strike. Quite simply it was thie lives and passengers on the line. Unlike Humans, you can't just replace a ocean liner when they Strike. The fact the White Star Liner immediatly announced refits for Titanic and Olympic further forced the shipping companies to fall in line.
35. Sailing ships are often senient, although it takes longer for them to Awaken than those with engines.
36. As computer systems were installed in locomotives, it was found the engines were pefectly capable on instinctually interfacing with them, allowing engines to eventually access the internet, and games.
37. Engines are capable of consuming human food, although wether they like to varys engine to engine. No one is quite sure where the food consumed food and drink go.
38. While the original 26 books of the railway series are based on actuall events on the NWR, they have often been tweaked to better works in their role as children's books