After a hard morning of tea parties, story books, and singalongs, not to mention a difficult negotiation over mac and cheese for lunch, Ben puts Betty down for a nap. He's promised to take her to her favourite park in the afternoon. It's a ten-minute walk away, so he won't have to break Kate's driving directive. He'll trade cars with Barnaby tomorrow - he's not sure the car seat will fit in the convertible's backseat safely, and his gran doesn't approve of flash cars.

He's exhausted, despite sleeping deeply the night before, and he wonders how John and Sarah manage while working, even with childcare. Things will get easier in the fall when Betty starts early education, but Ben is glad he can lend a hand now. He wants to be more than just a token godfather who sends a present now and then.

His own father was absent much of his life, seen on holidays and the occasional long weekend; more at the insistence of his grandparents, he'd always felt, than from any paternal instinct. Ben hasn't been back to Wales for more than two years, not since his aunt and uncle's golden wedding anniversary. He barely spoke to his father then and hasn't spoken to him since.

But he knows the estrangement isn't just his father's fault. He was his mother's ally, even after she no longer needed one, and while he doesn't regret that, he does regret how shallow his Welsh roots are. He doesn't want Midsomer to go the same way, even if his life is in Brighton now. His gran is getting too frail to live on her own, has been talking about a retirement community near the sea or moving in with his aunt, and that will be another tie severed.

But he still has a link here, in this house, one made tangible by the tiny fingers still loosely resting on his wrist, and he'll be damned if he lets it slip away. Even before this undercover gig, he hasn't been back enough, just flying visits between cases to see his gran, only occasionally sneaking in lunch or dinner with the Barnabys. He needs to do better.

It was hard, being back in Midsomer, being so close to family and friends, and unable to reach out. Maybe that's why he slipped so seamlessly into Jack Morris's skin. He couldn't be himself here; not and do his job properly.

Except Barnaby is right, as he usually is. Jack Morris is just a name. A persona isn't a person, and he's never been much good at acting anyway.

It was fine when he was just playing cricket, or digging behind the scenes, but once Barnaby came into the picture, everything changed. He was rumbled as an impostor, and he felt like one. It's no wonder Winter was suspicious of him. He appeared guilty, because he was. Not of murder, but of deception.

"You know me better than that," he told Barnaby, meaning more than just crime scene procedures, hoping Barnaby would understand that he wouldn't keep him in the dark without good reason.

Barnaby's cool response that he thought he did stung, as it was meant to, taking him back to the early days of their working relationship, when it felt like Barnaby disapproved of everything he did. There were times in those first few weeks when he considered requesting a transfer, the thought of disappointing a Barnaby, even a younger cousin, too much to bear.

But there had been glimmers of promise, too, quiet words of praise and angry concern that kept him going. And in the end, Barnaby - both Barnabys - made him a better detective. And being part of this circle of family and friends has made him a better person.

"Hold tight," Tom Barnaby told him, when he'd ended up in A & E after trying to take down a burglar on his own. "John takes some getting used to, but then so do I, and you did all right."

But Tom had chosen him. John was stuck with him. That made all the difference. Ben hurt all over, and he wasn't looking forward to explaining to John Barnaby why he looked like he'd gone a couple of rounds in the ring with John Kinsella. "He's going to think I'm a waste of time," he moaned, that hurting more than a couple of well-placed blows.

"I think you'll be surprised," Tom replied. "But if I find out you've been chasing after criminals on your own again, you'll be hearing from me."

Ben was surprised when John showed up in the A & E not half an hour later, but only as long as it took to realize that Tom had ratted him out. But instead of the expected bollocking, he was surprised again by John's genuine - if understated - concern.

"I know it may not feel like it yet, but we're partners, Jones," he said. "You don't go haring off on your own, and if you get so much as a stubbed toe on a case, you call me."

It sounded like a bollocking, but it felt more like the scolding his gran gave him when he tried to jump his bike over Mullins Creek. And the hand, warm between his shoulder blades made him feel better than the paracetamol with codeine.

Barnaby was angry then, but not at him - the look he gave the burglar handcuffed in the other cubicle, made even Ben flinch. It occurs to Ben that Barnaby might have been disappointed to find him working undercover in Lower Pampling, but that doesn't mean Barnaby is disappointed with him. It's easier to grasp the distinction when his head isn't aching, when the case is solved, when he's been trusted to care for the person Barnaby considers most precious in the world.

Jack Morris won the C10 Slam, but Ben Jones is Betty Barnaby's godfather, and he'll take that over a trip to Australia any day.

Except Sarah only confirmed what Ben already suspected - he wasn't Barnaby's choice for the job. And that's what it's always boiled down to - he has never been John Barnaby's choice.

He rubs his temples, trying to push back the first tendrils of a headache. Kate was right to put him on the bench. He only gets maudlin like this when his head is messed up.

He wasn't completely honest with Barnaby about that sting operation. It's true that he wasn't admitted to hospital, but he did spend the night in A & E, dazed and sore, but mostly feeling sorry for himself. It wasn't as if he had anywhere else to go.

He'd been holed up in Worthing as part of his cover, but he couldn't go back there and his new flat was filled with unpacked boxes and disassembled furniture. He couldn't even go to the station. His official start date hadn't been set yet, and his sudden appearance in Brighton would complicate the investigation.

In the end, he checked himself into a hotel for a couple of days, sleeping away the hours not spent in debriefings with Hicks and living on room service until he could face unpacking his new life. It was a crap Christmas, but he'll never tell Barnaby that. If Sarah found out, she'd be devastated.

He told Barnaby that he didn't leave a message for Kate because he didn't know who he was at that moment. He didn't call Barnaby, even at his lowest point, because he's never known where he stands with his former boss. He's Betty's godfather, he's Sarah's friend, but he doesn't know who he is to John Barnaby.

But that's not true. He remembers another concussion, another uncomfortable night in A & E, but this time he wasn't alone. Barnaby took him to hospital himself, when he refused to get in the ambulance, stayed with him while they poked and prodded and finally decided Grady Felton hadn't permanently scrambled his brains, and then took him back to his own home, ignoring Ben's token protests.

He remembers waking up in the now familiar spare room, disoriented and afraid, and looking over to see Barnaby sleeping in a chair next to his bed. Ben let him sleep; just his presence had been enough to calm him.

And he remembers waking up early Monday morning to find Barnaby watching over him, his three questions at the ready. He's not Barnaby's sergeant any more, but that doesn't seem to matter. He wonders if it ever did.

"You know John and Sarah adore you," Kate said. He didn't, of course, any more than he'd known that Kate was interested in him as more than a friend. He's been wrong about a lot of things, but for once he's glad to have been shown up.

He knows now that if he'd called Barnaby and simply said, "I need your help," Barnaby would have driven down to Brighton and taken care of everything. Because that's the kind of man John Barnaby is. It's not Barnaby he's ever doubted, it's himself.

It's past time he starts trying to call him John, at least when they're not working. It will be too confusing, even in his mind, (especially in his mind, his inner Barnaby says), with two DCI Barnabys in the house tomorrow

His phone pings with a text alert and he scrambles to silence it before Betty wakes up. He glances at the message.

Who's the Chancellor of the Exchequer? And where do I find the requisition forms?

Ben smiles. He's not sure about the first question - though that has nothing to do with the concussion - but he knows the filing cabinet like the back of his hand.

Second drawer from the top. Under R. Did you break another stapler?

Another text arrives a few minutes later. How on earth do you fill these out?

Either Winter is showing some backbone and refusing to do Barnaby's paperwork or Barnaby – John – is on his own in the office. Bring it home. I'll take care of it. He doubts it's the only form John has stuffed away in a to-do folder. It's been three years, but some things don't change. And he's always liked being of use.

Maybe that's where he stands with John Barnaby. At his back and by his side, and anywhere he needs him.

He sends another text. George Osborne. And no, I didn't look it up.

And then John texts him a check mark and a smirking face, and Ben wonders if the concussion is worse than he thought and he's seeing things. Winter must have taught him how to use emojis. He chuckles quietly. Maybe he's not the only one learning something new.

He knows he's not going to call Barnaby the next time he ends up on the losing end of an altercation. Some habits are just too deeply ingrained. But knowing that he could is enough.

"When you get older," he tells the sleeping Betty, "remember that even if he can be a grumpy sod, your dad's an old softie."

She stirs at the sound of his voice, but doesn't wake, so he settles into the chair at the side of her cot to watch over her. He still can't remember the lullaby his gran sang to him, but he knows other songs, and he sings them to her softly as she slumbers.