It's the night before Christmas but that's the last thing I care about right now.

I stare at the dot on the radar screen, willing it to disregard all the laws of physics. Thunderbird Three is making her slow climb out of the Earth's gravitational field towards her sister ship in orbit, but I want her to be outside the airlock now, if not ten minutes ago.

Mid-January, the doctors had said; three weeks from now. John and I had rearranged our shifts so I would be back down on Earth in plenty of time for the birth of Tin Tin's first child. But the baby, it seems, has other ideas and a few hours ago Tin Tin went into labour.

There's one thing you can say about my family - we are used to dealing with emergencies. As soon as she raised the alarm, the operatives of International Rescue swung into action. Dad elected to fly Tin Tin, Kyrano and Brains to the hospital in Auckland in the family jet, while John and Scott blasted off in Thunderbird Three to collect me. Back on the island, I know Virgil and Gordon are prepping the plane I will need to fly to the mainland.

I find myself pacing the gap between the console and the window. Looking down, the patch of blue ocean between Tracy Island and New Zealand is small enough to cover with my thumb. I think about the little plane crossing that space with its precious cargo. Will it reach its destination in time?

At least I'll soon know the answer to the question that has been bugging me for months. Tin Tin has been adamant that she didn't want to know the sex of our child before it was born. I know for a fact that Gordon has been taking bets on the result.

A beep from the console has me dashing back to the communications panel but the features that appear on the screen do not belong to Dad or one of my brothers, but Grandma's friendly face.

"Hello, dear. I thought I'd call and see how you were getting on. I knew you'd be fretting."

I don't see any point in denying this; sometimes Grandma knows me too well for comfort. I flop down in the chair in front of the console. "I'm just worried that they won't make it in time."

She gives me a reassuring smile. "Don't worry, it's going to take a while yet. Remember what you learned at those ante-natal courses you both watched. This is Tin Tin's first child; it will take her body a while to work out what to do."

"But the baby wasn't due for another three weeks! Won't that cause complications?" Even I can hear the note of near-panic in my voice.

Grandma shakes her head, still smiling. "Back when your father was a boy my friend Marjorie was the town midwife; she used to say babies come when they're cooked. She told me that after the first eight months of growing and developing, a baby is just putting on weight for the last four weeks. If anything, it will make the delivery easier for Tin Tin if the child is smaller. So calm down; you know she has Brains monitoring her throughout the flight and I'm sure everything will be fine."

I take a deep breath and make an effort to relax. "I was thinking earlier, Grandma. You brought us up to believe that punctuality was one of the virtues, and that it was almost as rude to arrive too early as it was to be late. It looks as if this baby still has to learn that lesson."

Grandma gives a mock frown. "Yes, I shall have to have words with my new grandchild when you bring him or her home. Fancy causing all this fuss and disrupting our family Christmas! But for now, young man, go and pack your bag and change into civilian clothes; your brothers will be with you soon. And stop worrying!"

I do as I'm told, though before Thunderbird Three makes her final approach I realise that once again I'm pacing the control room. After the rocket has docked, the next few hours pass in something of a blur as I travel back to the island then make a quick transfer to the waiting jet. On touching down at Auckland I change modes of transport once more to the rental car that my brothers have arranged to meet me at the Tracy Corporation hangar.

I drive out through the airport gates under a grey early morning landscape, the sky showing a hint of gold on the eastern horizon as I point the car towards the city. At this hour on Christmas morning there is very little traffic in either direction along the motorway. I keep my foot hard down on the pedal but, as often when I'm behind the wheel of a fast car, I start to relax. The latest update John has relayed from the hospital tells me everything is going well, and for the first time I start to feel that I might get there in time. I even find myself humming a little tune.

There's another car on the road ahead but, as I move out to pass, it starts to weave across the lanes, as if the driver is losing control. I don't know what this guy is up to, but I want to give him plenty of room, so I hang back. Suddenly he veers off the road, passing across the hard shoulder and coming to an abrupt halt with his front wheels embedded in the roadside embankment.

I pull in behind the stricken vehicle and approach, not sure what I'm going to find. On opening the driver's door I discover a middle-aged man dressed in airport security uniform. His complexion is grey and sweating, his lips blue, and both the grimace on his face and the way in which his hands grip the steering wheel tell me that he is in acute pain.

I crouch down by the driver's side and feel for his pulse. The thin and rapid beat confirms my initial diagnosis. "Sir, I think you are having a heart attack."

The man gives the briefest of nods then releases one hand from the steering wheel to gesture down to his side. "Pills," he gasps, "pocket."

I fish in his pocket and my fingers touch a small bottle from which I extract a pill and place it under the patient's tongue. "That should ease the pain," I tell him in my best reassuring-a-rescue-victim-tone. "I need to call for an ambulance; I'll be back in a minute."

I move back so until I am out of earshot and raise my left arm. "Calling International Rescue. John, can you patch me through to the local emergency services? I've got a suspected heart attack victim here."
John's face appears on the watch dial. "I wondered why you'd stopped moving; I've been tracking your signal. Dad just called; Tin Tin's gone into the delivery room. OK, you're connected."

As soon as I hear the voice of the emergency operator I give the details of what has happened then return to the car. Already I can see an improvement; the man's skin is now pale white rather than grey and his features seem more relaxed. I take hold of his wrist to check his pulse and he turns to look at me.

"Thanks for stopping, mate, " his voice comes out as a dry whisper. "It was lucky for me you were passing."

"No problem," I reply, forcing a smile. No need to mention the International Rescue ethos ingrained into every cell of my body that would not let me pass if someone needed help. No need either to let this man know that inside my head another Alan is screaming and kicking at the walls over the delay.

After what seems like an eternity but is probably only fifteen minutes I hear the approach of sirens and soon an ambulance is pulling in beside us.

As soon as I've given the ambulance crew what details I can, I jump back in the car and am on my way, with my foot flat down on the accelerator. I toy with the idea of contacting John for another update, but I know I can't get there any faster than I'm doing now.

At the hospital entrance I take the turning signposted 'Maternity' and the first person I see as I draw up outside is my father, wearing a grin that threatens to split his face in two.

If Dad is waiting for me outside, does this mean ...?

My father nods at my unspoken question. "Yes, son; about half an hour ago. It's a boy. Congratulations!"

A boy. I have a son. I can feel my mind trying to digest this fact, but first there's something else I need to know. "Tin Tin? Is she...?"

"She's fine; tired, but that's to be expected. Come on, I'll take you to them. Kyrano's with her now."

Dad leads the way inside through a maze of passages to a room where Kyrano is sitting on a chair outside the door. As we approach he jumps to his feet and gives a bow that is more of a bounce. "My daughter wished to sleep so I left her in peace. Congratulations, Mr. Alan." I notice that he too is wearing a huge smile, a stark contrast to his normal tranquil expression.

I hesitate. "Is it OK to go in?"

Dad gives a quick laugh. "I'm sure Tin Tin won't mind if you want to introduce yourself to your child." Then he turns and places his hand on my shoulder. "This is a moment to treasure, son. You'll never forget it." He and Kyrano exchange knowing smiles, and, looking between them, I realise that I have now been promoted to the ranks of fatherhood. I can feel a unique and special bond with my own father and father-in-law, a bond that my brothers do not yet share.

Feeling ten feet tall, I push open the door and tiptoe in.

The curtains are drawn, admitting only a dim light, but I can make out the huddled shape of Tin Tin lying curled on her side. Beside her bed I can see a small transparent box on wheels. Trying to make as little noise as possible, I move closer until I can peer down on the tiny form swathed in blankets. My newborn son's face is red and screwed up in an expression of intense concentration and his eyes are pressed tight shut, while a tuft of dark hair sticks out from the top of his skull, but I don't think I've ever seen a more beautiful sight in the world. Dad was right - I'm never going to forget this moment.

Just then I feel something touch my wrist and look round. Tin Tin has woken up and is reaching across the bed.

"Hello, sweetheart," I keep my voice low. "How are you feeling?"

She gives a wan smile and gestures for me to sit on the edge of the bed. "A bit tired and sore, but I'll be fine." She gestures towards the box. "What do you think of him?"

"He's ... he's beautiful!"

"More beautiful than Thunderbird Three?" she replies in a teasing tone.

"Yes!" I say, and mean it, then add, "but don't tell my brothers I said so." I put my arms around her as gently as if she's made of delicate porcelain, easing her over so she is leaning against my side. I kiss the top of her head. "Honey, I'm really sorry I wasn't here in time; I so wanted to be."

"Don't worry, Father told me what happened. You stopped to save a man's life; that is the kind of person you are, and I love you for it. I am sorry that the labour started so early. It looks like our son is going to take after his father - always in a hurry to get where he wants to go." She threads her fingers through mine, then turns, kisses me gently on the cheek and whispers three words that melt my heart.

"Merry Christmas, Daddy."