This scene is perhaps my favourite Matthery scene. They walk off the cricket pitch together, discussing their plans for the future - their baby and Downton. They're a team, they're partners in every aspect of their lives.
Matthew tells her "I hope I can count on you not to laugh when I drop the ball", another of the many examples of his dry, witty, self-deprecating humour. But Mary takes it to a deeper, more serious level, when she says "You can always count on me", and she accentuates those few, profound words with a tender caress to the side of his face. You can always count on me because no matter what, I'm always going to be here for you. She's saying "I love you" with her EYES.
"I know that", Matthew answers as he looks into her eyes. THE WAY HE LOOKS AT HER ASDFGHJKL
The thing about this scene is that you can feel how much he loves her. How much they love each other. His adoration is so evident, so visible, it's radiating from his eyes and every word he says. "I didn't think it was possible to love as much as I love you." This is from Matthew, who has such a big heart, and he's telling his wife that he loves her more than he ever thought he could love another living soul, he loves her beyond human capacity. THAT IS DEEP.
Robert interrupts the lovers, impatiently calling Matthew back. Matthew looks back at her, saying, "I've got to go." What he's really saying is: "The last thing I want to do is leave you, but I've got to." Mary answers, "Of course you have", with that loving smile. Translation: Go and play cricket. I'm always going to be right here. Kiss me to your heart's content later.
He understands her unspoken message as he always does, and suddenly he can't help himself, he has to give her one last kiss before he goes off to play, just to show her what she means to him. He dives under her hat, and the kiss is sweet and short and yet it means SO SO MUCH. Matthew's eyes meet hers, and he grasps her hands briefly, to tell her "I'll come back and continue this as quickly as I can, my darling." He turns and runs off to join Robert (who, by the way, WAS IN THE BACKGROUND WATCHING MATTHEW KISS HIS DAUGHTER IN PUBLIC) while Mary looks after him adoringly. SHE IS SO IN LOVE.
Sorry about the rant, I'M IN LOVE WITH THIS SCENE. And, of course, Matthew.