Solidarity, Sister.

I can still remember the shock I felt, the first time I sat on a packed Glasgow commuter train and heard everyone talking to one another like old friends. It depends where you were brought up, I suppose, where you land on the spectrum - London probably only second to Moscow at the opposing end of the scale. It doesn't take long for people to get the hang of it here in town. Paradoxically, in situations where we accept you have no personal space whatsoever (Victoria line at teatime, anyone?), we become fiercely, aggressively, insular. A packed train is a bizarrely quiet place.

I just love the way having a two-year-old exempts you from this game. Having a little chap who can name half the lines on the underground, hang onto the handrails like a  performing chimp and sit on a packed train in the evening peak, studiously digesting his upside-down copy of the 'Standard', all to order, somehow permits you to speak to your fellow man, or, if that's taking it a bit too far, at least smile at someone.

An effervescent small child is a must, therefore, if you long to break the rules of (dis)engagement, particularly in London. You can rib the middle aged men who are beaten (wilfully) to giving up their seat by an elderly lady, when it becomes apparent that actually the little fella prefers to stand. You can, pretty much whenever you like; play the 'come on, I've got a two year old on my shoulders and you're still holding me up' card when people start pratting about with suitcases you ought to have an HGV licence to tow, right at the foot of an escalator - knowing they are so much less likely to give you a mouthful back or rearrange your teeth when the little boy on your shoulders with whom you are conversing out loud is beaming at them like an angel. I love it. We both do, actually.

As with all performance arts, though, the adage 'never work with children and animals' rings true; sometimes, you get more than you bargained for.

Which is how I came to spend the best part of five hours last night with a weed addict from Camden.

Sat in the waiting room of the railway station in Mummy's home town, with an hour to kill before the dreaded 'hand-over', it became time to do a walkabout. Everyone, willing or not, in that waiting room, was subjected to an illustrated lecture (thanks to the photographs we'd just printed in Asda) on our first full week together at home for ten months. One man, so shocked at your introductory technique of sneaking up behind him and attempting to walk between his legs, made his excuses and went to sit out on the platform.

As time passed, people came and went, until eventually just one lady remained, who'd been there when we arrived. It must have been something to do with your fixation with trains, that the conversation which inevitably takes place between apologist parent and joe public (we'll call her 'Kelly') turned to the prospects for fare dodgers.

"What do you reckon my chances are?" she asked.

I knew she wanted to get to London - just as I'd walked into the station earlier, I'd seen her looking at the fares on the ticket machine, before walking away frustrated towards the platforms.

Cut a long story short, Kelly had a long story to cut short. Just like me.

Kelly has a little boy. He's ten. She'd come to drop him off after a week in London, too.

Kelly had a difficult upbringing. Her Mum had been an addict and died too soon. For the first seven years of his life, her son had lived with her, and barely saw his father. Whilst concerns about her son's welfare had never existed, eventually she decided that she wanted to rid herself of her own addiction; to do the best for her son, she brought in social services, contacted his father, and set him up with a new life with his Dad whilst she went into rehab. She was philosophical about his prospects - as much as she struggled with his father, she believed that the lifestyle, the education and the environment in the west country would be to her son's advantage. She still has him for almost all of the school holidays.

Kelly is a brave woman. I lost you because you were taken from me. Kelly let her little boy go, to try to do the best by him in difficult circumstances.

Having satisified myself as to the plausibility of her plight (she'd missed her National Express coach home, for which she showed me the tickets), I said I'd help her, since I was going back the same way once I'd dropped you off.

When I came back from the worst bit of the week (watching the mother who hit me and the father who she says hit her taking you away from me for another three weeks), I handed Kelly a ticket to London.

She burst into tears and hugged me for all she was worth.

"Why me?" she asked. "I don't deserve this!".

The journey home was an interesting one. We got on the train and sat down to find that someone had left a CAFCASS compliments slip on the table. Kelly knew CAFCASS. As ever, they'd proved more damaging to her son's childhood than any of the other difficulties he'd faced.

The conversation came round to faith. Of the two books Kelly had read in her life, one had been a children's Bible, when she was in rehab. Rehab hadn't gone smoothly - but the good book had stuck with her. She was desperate to know and understand more, but nobody had ever given her the chance.

Kelly's life, as she told her story, was to me the epitome of the real story of so many of those people we see on the tube - she felt lonely in a crowded place.

Amidst the noise of the world, she was craving a 'still, small voice of calm'. The 'I'm alright Jack' charade was merely that.

She felt ashamed. Worthless. A Failure. Her dreams to be clean of drugs, to get a job, to find some meaning in life, seemed to her to be beyond her grasp, undeserved even, as the tears returned.

Her heart bled for her son, setting out in life in conditions she never would have chosen.

As we sped into London, I realised that we had a lot in common.

Telling her so, she berated me. "But you're a fantastic Dad - just look at you and your lovely little boy. You're a lovely man. Look what you did for me tonight".

I was back in the counsellor's chair. This lady, for all that she had suffered, for all that she struggled to understand, had a word in season for me, too. We both needed to be told we weren't condemned.

I don't know if Kelly and I will cross paths again, whether she will take up the invitations I made to come to church and learn more about the God who created and loves her. I hope she will. But I do know that I was preaching to myself as much as to her when I summed up our conversation and offered to pray for her.

"There was nothing in it for me to do what I did tonight, although the Bible tells me I did it for Jesus" I told her. "But seeing your reaction reminded me how I feel when I think of everything God's done for me - if you want to know more about what being a Christian means, hold onto that moment".

Thank you for sparking that conversation out of nothing, son. You played your part for the Lord tonight, too.

Miss you.

Love from Daddy.