Joan reaches up to stroke his arm a little as he's stroking her hair, reciprocating the affectionate touch. Lying here with him in the sun and the fresh air and with a comfortably full stomach is absolutely wonderful, and Joan feels happy and calm and content.

Then Ted accidentally hits Sherlock with her sandwich wrapper and she can't help an amused wince.

Sherlock takes it and tosses it into the can, then his own, then his empty water bottle. Nothing but net. He's got skills.