On a damp, overcast November afternoon in a patch of woodland near the top of Wrotham Hill, 22-year-old Jack Burdett is digging a hole in the ground.

He's not the only one. A group of volunteers have been doing the same thing, probing the woodland soil with metal rods for the best part of an hour, "venting" the earth so sniffer dog Jessie can get a better scent, occasionally stopping to swap rods for spades and cut down into the ground.

But it's the sight of Jack that stops the others once in a while in their tracks - because it's the sight of a young man digging to find the body of his mother, and it's not an easy one to behold and process.

"Are you sure you're OK Jack?" asks Sharon Brine, who's been heading up the Search for Sarah Wellgreen (SFSW) team since Jack and his brother Lewis's mum disappeared from her home in New Ash Green last October. No doubt Lewis would be here too, if he wasn't having to carry on with army training in Yorkshire - which in itself is testament to his own strength of character.

"Yeah, I'm fine," Jack replies between breaths in the cold November air, and he carries on digging with his friend beside him.

At least he's got a friend. Just under 15 miles away, idling in a cell in Belmarsh prison, is the one man who could end this toil in the woods, and the one man who's responsible for it - 39-year-old Ben Lacomba, who up until October 9 last year had been living with Sarah, his ex partner and the mother of his own three children.

Ben’s digging was done the night he killed and buried her, but he dug himself a hole that night too, and now he sits alone with his thoughts while others try to trace the footsteps he took in the early hours of October 10, 2018.

Only he truly knows how his mind got twisted to the point that the desire to murder emerged from it, then consumed it; and only he knows exactly where that dark journey led him - the hidden piece of Kent where he thought he could rid himself of Sarah once and for all.

"Where's Sarah?" prosecutor Alison Morgan barked at him a year later in Woolwich Crown Court, while a large map was held up in front of him. "Have a look at that map... You help us now. Where is she?”

Up in the public gallery, like a pack of hunting hawks perched on a cliff-top, Sharon and the SFSW team - Gareth, Shaun, David and Tracy - looked down at Ben, then the map, then back at Ben; and the police in court did too, straining to see if a subconscious dart of the eye might finally give it away. But Ben stared blankly ahead.

Sharon and the hard core of the team had been up there in the gallery following proceedings for most of the trial, looking down on the courtroom just as they might look down on the Weald of Kent from the top of the North Downs at Wrotham Hill, scanning the patches of woodland across the countryside vista stretching out for miles into the distance.

Occasionally, while the police evidence was being laid out by prosecutors, Gareth would turn and look straight down on Ben in the dock with a fixed stare for minutes on end, as if trying to bore through his skull and into his mind for further clues. But Ben gave nothing away, his face fixed with same blank expression flecked with the faintest hint of malevolent arrogance.

Together the team traced a mental map as they heard how Ben's red Vauxhall Zafira took a winding journey south from New Ash Green on the night Sarah disappeared, captured on CCTV in Church Road, Hartley Hill, Pease Hill, and Plaxdale Green Road; but it's there the car disappeared off that CCTV-lit map into darkness for two hours, before returning the same route two hours later.

Where did Ben go after Plaxdale Green Road? Well, in all probability to a narrow lane that could surely not be more aptly named - Labour-in-Vain Road - because that's where Plaxdale Green Road leads to; but beyond that, the guesses get less and less certain with every half mile and road junction.

And it's about 300 metres north of Labour-in-Vain Road that Jack, Sharon, and the search team find themselves on this dank Sunday afternoon, six days after a jury declared Ben guilty of murder at Woolwich.

They've moved out of the woods by now, scrambling over a barbed wire fence, and up into two sloping fields divided by a hedgerow interspersed with oak and holly.

Sharon explains they've been brought here by a fresh lead from a farmer, who reported having seen lights in this field near the hedgerow around the time Sarah disappeared.

"It had been playing on his mind," she says, as the team probe under the holly. "He said if he was going to bury a body it would be in there."

But other members of the team look doubtful. Would Ben have really driven into a field with his lights on in view of a nearby farmhouse? And come to think of it, would he have chosen the woods they'd just been in - woods that border a campsite, Thriftwood Country Park, which are often used by dog walkers?

Out in the field it's starting to rain, but the team carry on scouring the hedge for suspect areas of disturbed earth, until eventually the decision is made to head back into the woods.

Jessie the sniffer dog - or 'cadaver dog' - has been taken home by owner and handler Tony Warren because she'd started limping, but they decide to dig into a patch of ground where she'd reacted earlier.

The light is beginning to fade, and there's a shared sense of desperate frustration among the diggers as the last hopes of the day fade with it.

"I'm gutted," says Sharon looking on. "I thought this was going to be it."

But Sharon's been here before, countless times. Ever since she began taking down names at the start of the volunteer search effort - when Sarah was still thought to be possibly alive and a 1,000 people turned up to help find her - every day has begun with fresh hope, and ended with hopes pinned on tomorrow.

A year on and numbers have dwindled down to the SFSW hard core: workplace mental health trainer Sharon, 60; painter and decorator Gareth, 41; foodbank volunteer Tracy, 42; student Shaun, 19; and commodities consultant Dave, 41 - plus graduate Megan, who helps with social media, and a wider group of villagers who lend their time when they can.

"Every day used to start with 'where am I working'?" explains Sharon, back at home the following week, the day before Ben Lacomba is due to be sentenced. "Now it's 'what are we doing with the search'?"

"Some friends and family don't get it, and they don't get why I'm still involved. Sometimes I think what the hell am I doing?

"I've been in the pitch black crawling through a Hawthorne hedge to get out of a field. We've been down at Greenhithe in the pouring rain.

"We've walked miles and miles with shovels; or you're skidding down slopes on your backside at Exedown Woods, or you come across a sheer drop, and you think 'I don't need this.'"

But Sharon and the team are not going to give up. She talks of "when" they find Sarah, not "if", and her determination is driven by the empathy she felt when she first saw a post on Facebook, from a young man asking for help to find his mother.

"It could so easily be anybody else", she explains. "Anybody else could be in that situation - and would they hope the community came out for their family? Yes. It's the kind of ethos people have in the village. People are so invested in it. I can't walk across the village without people asking how it's going."

Barring Sarah's family of course, no one is as invested as Sharon and her team, who have grown closer as the weeks of searching turned into months, and now a year.

"That's the strange thing," adds Sharon. "There's six of us and a big age range, but now we're all good friends. The other day there was no court and no search, but they were all here drinking tea."

That might be a cosy image; and perhaps, to a cynical killer, it might be an amusing one. The sight of Jack Burdett trudging home through a wood in the failing evening light with a shovel in his hand is neither.

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