'Trucker's Dog Saves Toddler,' the headline halfway down the front page of the Western Post declared.

The paper was nearly a week old, saved for Daniel by the owner of the roadside burger van where he'd bought his breakfast. He was parked not 20 yards from it now, in a lorry park on the side of the A386 between Tavistock and Okehampton. It was a designated picnic spot, but at this hour of the morning, there were more trucks than cars.

Pulling a wry face and shaking his head, Daniel Whelan took a sip of his latte-to-go and read on, his booted feet propped up on the dashboard of the lorry.

When farmer Peter Daley (58) and his wife, Sally (56), discovered that granddaughter Emily had been missing on their 135-acre farm near Launceston for over an hour last Saturday morning, they feared the worst. Peter and Sally aren't normally overanxious grandparents, but in this case they could be forgiven, because four-year-old Emily, who was staying with them for the weekend, is profoundly deaf.

'I thought she was with Peter and he thought she was with me,' Sally explained. 'We were especially worried because there were tractors working in the fields and the men might not have noticed such a small child. We were at our wits' end, not knowing where to look first, and of course it was no good shouting, because she couldn't hear us.'

Things might have looked very black indeed for little Emily if fate hadn't intervened in the shape of delivery driver Daniel Whelan and his ex-police dog, Taz.

When truck driver Daniel (28), who was delivering animal feed to the farm, heard what had happened, he offered the services of his German shepherd dog to locate the little girl. Taz had served 18 months with Bristol Police Dog Unit before being injured in the line of duty and retired last year. As a police dog, tracking was part of his work, although in those days it would have been runaway criminals that he trailed rather than lost children.

Shown a cardigan belonging to little Emily to give him the scent, Taz soon demonstrated that he had forgotten none of his skills, finding the lost child within ten minutes, playing in a hay barn just feet away from a herd of cows.

'Thank goodness the dog found her when it did,' Sally Daley said, still clearly shaken by the memory. 'Cows are generally placid, but they can be unpredictable – I dread to think what might have happened if she had wandered in among them.'

Daniel, who works as a driver for Tavistock Farm Supplies, preferred not to be interviewed, saying that all the credit belonged to three-year-old Taz, who travels everywhere with him in the lorry.

All's well that ends well on the Daleys' farm. Thanks to Taz, Emily is none the worse for her adventure – in fact, she has gained a new friend, 42-kilo Taz, proving that while he might have been tough on criminals, he is just a gentle giant at heart with a soft spot for little girls.

Daniel had to smile at the last line. The article was illustrated by a picture of Taz sitting dutifully with the child's arms wrapped round the thick fur of his neck, but to Daniel, who knew him better than anyone, the expression on the dog's face was one of slightly pained resignation rather than pleasure.

He held up the paper, turning to where Taz sat at the other end of the bench seat.

'Look, Taz, you're famous.'

The German shepherd thumped his tail on the seat a time or two and edged nearer, but his attention was firmly fixed on the dashboard, where a paper bag sat, containing a bacon and egg roll.

'If you're gonna start drooling, you can sit outside!' Daniel warned severely, but the dog wasn't fooled. He moved even closer, his gaze never wavering, knowing from experience that the last bite of bread and bacon would be his.

Moments later, the butty was forgotten as Taz threw himself at the passenger window of the cab, barking furiously. A sharp word from Daniel calmed him a little, but he remained on edge, growling ominously and hackles up, while he watched a small black Staffordshire bull terrier trot jauntily in front of the lorry and away at the heels of his cab driver owner.

'What? That scutty little thing?' Daniel teased. 'You'd make mincemeat of him. Here, have a bit of bacon.'

The German shepherd accepted the morsel, licked his lips and grumbled some more. He'd had a bad experience with a Staffie when he was just a pup and it would require more than a tasty bribe to take his mind off this one.

It was a cold, wet day and it was with a sigh of relief that Daniel climbed back into his cab after the last delivery that afternoon and prepared to head for home. He had finished early and with any luck would miss the worst of the Friday traffic.

Not that thoughts of home were particularly enticing just at that moment in his life: with a limited budget and the necessity of finding somewhere that he could park the lorry from time to time, the only accommodation he'd been able to find had been a one-bedroom flat above an empty shop in a lane off the Tavistock to Launceston road. The unoccupied downstairs space had most recently been a lawnmower showroom and still had the oil stains and stink of petrol to prove it. However, the property had scored on three important points: the rent was cheap; it had a good-sized car park at the back; and it was sufficiently removed from the nearest village to avoid upsetting anyone when he started the lorry's V12 engine at the crack of dawn.

The light was poor under an overcast sky, and the windscreen wipers swished monotonously to and fro, barely clearing the fine drizzle before it obscured the glass once again, making the headlights of oncoming vehicles star and spread.

All in all it was a dreary afternoon and there was nothing to stop Daniel's mind dwelling on the depressing turn his life had taken. Just three short months ago, he had had what he thought was a stable home life with a wife and eight-year-old son, a career in the police force and a circle of friends. Now, entirely as a result of his own actions, he had none of these and the realization was still raw every time it hit him.

The fact that it could be regarded as questionable whether friends and colleagues who had shown themselves to be so fickle were worth mourning gave him no comfort at all. There had been many times lately when he'd wondered if, given that period of his life over again, he would make the same choices, and he found he just didn't know.

Daniel rubbed his eyes tiredly. Such reflections were pointless. The decisions had been made and he had to live with the consequences. End of story. He switched on the radio, reaching across to ruffle Taz's soft coat. Lately the dog had become the only constant in his life.

Taz rewarded his caress with a flattening of his ears. Daniel suspected that he, at least, was very content with their altered circumstances. Amanda hadn't allowed the dog in the house, complaining that his constantly shedding coat made work for her, so for the first part of his life Taz had mostly lived in a kennel and run in the back garden. It wasn't so bad when the dog was working, but after he'd been forced to retire, Daniel had hated leaving him shut in while he was on shift. Now, the dog had his company twenty-four hours a day and a daily walk on the moor.

A sudden burst of the James Bond theme tune interrupted his thoughts, bringing with it a sharp pang of regret: his son, Drew, had downloaded the ringtone to his mobile one day...