For this particular story, Edith and Anthony did marry after the war. I wrote this with Father's day in mind and I believe that Anthony, having lost a child of his own, would have taken a special interest in his nephew throughout the boy's life.
"Mama", George called, popping his head into the sitting room, "I'm off to Uncle Anthony's and Auntie Edith's."
"George" his mother sighed, "why do you spend so much time at Locksley? Surely you must have better ways to spend your afternoons. I mean, aren't your cousins away in London visiting Anthony's sister at the moment?"
"Well, yes, but Uncle Anthony is meeting with a couple of the tenants on his estate today and I'd like to tag along."
Mary rolled her eyes, "What on earth for? You're sixteen for goodness sakes. Surely spending time with your uncle, who's well over sixty years old, can't be all that interesting."
"I know you think him dull as paint Mama but he's not. He's very intelligent, well travelled, and in quite good health for his age. In fact, I'm the one struggling to keep up when we're walking his estate. And, most importantly, he talks to me as though I'm a man not a boy. He listens to my problems and offers advice but has also taught me that I must make my own decisions and accept responsibility for the outcome. He's been like a father to me."
"But, why waste your time visiting tenants with the man? Wouldn't it be better spent with your grandfather, learning your role as the future Earl?"
"You see, that's part of the reason..." George hesitated briefly to consider how his mother might react. "When I become Earl, I hope to manage Downton as efficiently as Uncle Anthony runs his estate."
Seeing the look on his mother's face, he continued before she could speak. "Grandfather is certainly respected, here, and in the village but Uncle Anthony is respected and loved. He listens to everyone, treats them as equals, and sincerely cares about their well being. From what I've heard over the years, I think Papa would have ran the estate very similar to how Anthony does Locksley."
George's last statement brought tears to Mary's eyes as she thought back to Matthew's insistence on repairing the estate cottages.
"He's a good man, Mama. He looks out for everyone including those who've haven't been as kind to him."
"I assume you're referring to me?"
George nodded slowly, "you and Grandfather are rather hard on him at times, I think. Did I tell you, he's been teaching me to drive. I asked Auntie to but Uncle Anthony wouldn't allow it. Do you want to know why?"
"I'm sure you want to tell me" Mary answered dryly.
"He says Auntie Edith's rather a speed fiend and a bit too daring behind the wheel. He made me promise to always drive responsibly and not take chances. He said and I quote 'Young man, you must not allow your Mama to suffer another loss such as when your Papa died."
"I had no idea" Mary murmured meekly.
"Did you know he has a DSO for his work in military intelligence?"
Mary shook her head.
"Because he's humble and honorable as well as generous. I hope to be half the man Anthony is."
"I know you and Grandfather like to joke about how boring he is, Mama, but he's not. And neither is his and Auntie's marriage. Believe me!" George grinned. "Never open any door without knocking first and always, ALWAYS, wait until you've received permission to enter."
Later that evening after dinner...
"Edith, might I speak to Anthony alone?"
The strawberry blonde looked anxiously to her husband who gave her a slight nod.
"Of course" Edith agreed, kissing Anthony on the cheek, "I need to finalize some arrangements with Mama about next week's dinner party."
"Anthony" Mary began once they were alone, "I've noticed George seems to be spending a great deal of time at Locksley, particularly with you."
"If you'd rather he didn't" Anthony's voice trembled, the sting of rejection evident in his features. "I'm sure" he continued before being cut off.
"It seems he aspires to be like his uncle."
"Tom's certainly an excellent role model for the boy."
"George wants to be like you Anthony. It's you he admires."
"You don't say!" the older gentleman smiled, still uncertain where this conversation was headed.
"Yes, we had a interesting discussion earlier in which he named quite a lengthy list of your merits. And, well, I wanted to thank you for taking my son under your wing. He's very lucky to have a man like you in his life to show him what being a proper gentleman involves. You've been a positive influence and I wanted to express my appreciation."
"Um... I...um, thank you Lady Mary" the baronet stuttered, "Master George is a splendid lad. I quite enjoy our time together."
"I'm happy to hear it" said Mary with a light touch to Anthony's arm before taking her leave.
"I think that's a first" a bewildered Anthony remarked to his wife as she rejoined him.
"What did she do now?" Edith groaned.
"She was nice to me!"