I have a headcanon that the Mid Sodor essentially went through #2s the way Spinal Tap goes through drummers, and that the #2 in "Granpuff" was intended to be a composite character of sorts (at least in-universe). Unfortunately, Sir Handel did not take it that way at all, and held a pretty deep grudge against the Thin Clergyman for many years after Duke's book was published for how Stanley was ostensibly depicted (hence why there's so little about his trip to the Talyllyn Railway in Great Little Engines).
Sir Handel did reconcile with the Thin Clergyman and his family in time, and the Thin Clergyman would publish Stanley's story in the Island of Sodor book to make things right.
Over the years, Sir Handel's feelings have softened towards the book, and now he can simply enjoy those stories and reminisce about happier times on his, Peter Sam, and Granpuff's old railway. In particular, there's one illustration that Sir Handel has become particularly fond of.
All those years ago, his younger self keen to impress, Duke ready to show him the way, and in the back is Stanley sleeping peacefully, if somewhat annoyed. Sir Handel can just imagine it now...
Falcon wakes up bright and early, ready to pull the Boat Express.
"Another day, another express train to pull! And with this new coat of paint, I'm sure to dazzle everyone! Wouldn't you agree, Stanley?"
Stanley, meanwhile, is still sleeping after a long night out on the maintenance train.
"Wake up lazybones!", laughs Falcon, "aren't you supposed to up to pull the maintenance train again?!"
"Not for another hour", mutters Stanley.
"So Stanley, I suppose you're just gonna doze off with Granpuff?", chuckles Falcon.
Stanley simply keeps his closed in the hopes that Falcon will give up. He does not.
"Well, gee Stanley, it sure would be an awful shame if you were late", says Falcon innocently.
Stanley still has his eyes closed, but now his face is twisted up into a frown.
"Now Falcon", scolds Duke, "don't go telling Stanley he's late! You know how he gets when he's agitated."
"See Stanley?", grins Falcon, "even Granpuff is up before you!"
"When is Granpuff not up early?", retorts Stanley drearily.
"Yeah, yeah, yeah", says Falcon, "excuses, excuses, you just don't want to see me look good as I pull off for the express!"
Suddenly, Stanley starts to form a grin of his own. "Nah, I'd just rather see real express engines take off."
"What?!", pouts Falcon indignantly.
"Yeah", smirks Stanley with his eyes still closed, "you know? The Parla-mench, or whatever it is-"
"The Parliamentary", corrects Duke with restrained but evident annoyance. Two years later, and young Stanley is still doing this.
"Yeah, that", Stanley replies with satisfaction. Works every time. "Yeah, the Par-luh-mench-ury, ya know? Real fancy pants train, the one that Freddie sometimes takes."
"Well, yes", Falcon sheepishly admits.
"And Al!", continues Stanley, "yeah, Al is a hell of an express engine, ain't he?"
"Stanley!", admonishes Duke. Rather it's for the foul language or the improper English is anybody's guess.
"Al got somethin', ya know, Fal?", continues Stanley as Falcon silently fumes, "he got style, he got class, and you know, he's got something else."
"And what would that be?", huffs Falcon.
"Those special wheels", grins Stanley.
Falcon, predictably, fumes as he heads off for his train.
"Works every time", grins Stanley smugly as Duke rolls his eyes.
Sure, Stanley wouldn't have been built yet when that story takes place, but it matters not to Sir Handel. For him, all that matters is that he gets to have an illustration from the Thin Clergyman's books where Stanley is at peace, something he rarely ever got to enjoy in life.
However many years it's been since Stanley left their lives, Sir Handel has never forgotten him. When the television series was preparing to adapt the narrow gauge engines' stories for its fourth series, he asked Miss Allcroft and Mr. Mitton if they could have his model painted with red lining. He did this both for his late friend and for the railway that's been his, Granpuff, and Peter Sam's respective home for the past however many years. And later, he would have a portion of the illustration framed in the sheds so that Stanley would always be there just as he should have been able to.
They may not have been built by the same maker, or even in the same country, but Stanley was his little brother, and he always will be.
