With two young children and a home on the edge of the Yorkshire Dales National Park, he had become fascinated by conservation, nature recovery and the disappearance of once-common species of wildlife.
In February 2020, he and his wife Rachel took the plunge, buying an old farmhouse on the outskirts of Redmire in Wensleydale with 10 acres of land - and thus began what they hope will become one of the region's foremost independent rewilding projects.
Martyn has a closely-guarded secret list of the species he eventually wants to reintroduce - but is starting out with less controversial water voles, harvest mice and crayfish rather than the apex predators the local farming community fears.
The land will also be regenerated - the site on the banks of the River Ure is a perfect cross-section of habitats, with ancient woodland, grassland, scrub and a water course. He wants wildflower meadows to thrive and has already planted 3,500 new trees, sunk ponds and cleared non-native vegetation.
Mill Farm is self-funded, has enjoyed tremendous local support so far and will never need to generate a profit from tourism or other income streams - instead it will become a blueprint for how Martyn believes we can all live.
With no experience of countryside management - Martyn grew up on a Birmingham council estate, and fell in love with the Dales when he rented a cottage while working in Newcastle - he has had to cultivate a network as well as his land. He has struck up a friendship with 'guerrilla rewilder' Derek Gow, whose Devon farm is home to stork, beaver, wildcat and Iron Age pigs, and obtained grants from the Woodland Trust for necessary work such as fencing.
He is overseeing the ambitious transformation while still working full-time in insolvency and construction consultancy, having purchased the farm - which was part of the surrounding Bolton Estate until the 1980s - from its previous owners, downsizers who wanted to hand the reins to a local family.
"Mill Farm was grazed pasture, a grass graveyard. Our vision is to create a mosaic of habitats as kind of a demonstration project, and show how a small piece of land can inspire bigger things. Being on the river means we are a nexus point of habitats, an ideal crossroads."
Martyn passionately reels off the achievements he and Rachel, helped by sons Daniel, five, and three-year-old Rory, have accomplished in the past 18 months - partly thanks to lockdown giving them more time at home.
The ancient woods have been thinned out and restored, invasive species such as balsam removed, new trees planted to encourage hazel dormice (whose current range extends to around a mile away since they were reintroduced to Aysgarth Falls) and clearance work to promote natural daylight completed. The boys' contribution has been to build a bug hotel.
There is a perennial wildflower meadow which, unlike similar stewardship schemes, will be cut in September rather than July to benefit late summer flowers. Half an acre of new wetland has been created by digging ponds and trenches and widening an existing beck.
"We've doubled the amount of water, and added 1km of new hedgerows. We had to fence off eight acres because of the endemic rabbit problem - there were 16 warrens when we arrived. We got Woodland Trust grants for the tree planting, but we aren't using tree guards as we want them to grow naturally without the plastic."
Local ecology groups survey the site during regular visits, and have now recorded 68 bird species in 15 months. The five-year plan for Mill Farm to ultmately be awarded Natural England conservation status has, Martyn believes, accelerated during lockdown, and he has now ascended the first rung of the repopulation ladder.
Next September, 180 water voles bred on Derek Gow's farm will arrive in Redmire with the blessing of the Environment Agency and three neighbouring landowners who have agreed to join the project - two smallholders and Girlguiding UK, whose Guide campsite will become part of a wildlife corridor. He is in talks with a reptile expert about encouraging native slitherers such as adder and grass snake - though the large numbers of predatory pheasants in the area could preclude their recovery.
"I'm not from a conservation background, so I've had to build up a network from scratch. I emailed Derek and he rocked up here - he's been a source of inspiration and advice.
"We are in talks to become an ark site for native crayfish, which have been decimated in the Ure, and we can be a safe haven for them. The third species is harvest mice.
"I've always had a fascination with natural history, and I became sick of reading how rubbish things were becoming. It saddened me, but every day I was still driving to work churning out diesel in my car. Life felt soulless. I resolved to do something about it and make a difference.
"I earn a fraction of what I once did but I'm much happier. Local feedback has been phenomenol too - we expected resistance, but people have been lending a hand to help us."
He admits that the 200-year-old farmhouse itself is one of the most energy inefficient homes in Wensleydale, and work to take it off the grid has begun. He has also, regrettably, decided to no longer own dogs because of the disturbance they could cause to the wildlife he wants to nurture.
"I've got a list of species I ultimately want to bring back, but I'm not disclosing it yet and I'm being very careful, as we are surrounded by large estates which practice predator control. We need to work with them but it will be a long process. The habitat here is not the barrier - vested interests are, and we need reach a consensus between the different groups."
Though he deplores the attitudes which have made species such as red kite and fox - common in urban Leeds - rare in Wensleydale, Martyn accepts that control of non-native wildlife and vermin is necessary to ensure his fragile ecosystem can grow. Mink will have to be exterminated if water voles are to gain a foothold on his land.
"We control rabbits, mink and grey squirrels - we have had a red squirrel here and we are on the front line of conservation of them (there is currently a managed refuge habitat for reds at Snaizeholme, near Hawes, and they have begun to spread into Wensleydale).
"I used to be an armchair conservationist, with a 'live and let live' attitude, but the reality is you have to deal with non-native species, and it's not pleasant. But we're already seeing the benefits - the grazing pressure from rabbits has now eased. Before, if I planted a tree it would disappear within two weeks. It's a neverending battle but the rewards are immediate and we are seeing species coming here that weren't there before."
As well as the lone red squirrel, an osprey has visited his section of the River Ure - devoid of anglers as the farm includes the fishing rights - and willow warbler and kingfisher have been spotted. A new feeding station and nesting boxes have been installed specifically to target tree sparrows, whose population has crashed.
"We're trying to attract birds that were common on farmland 20 years ago, like barn owls, tree sparrows and starlings. Conservation starts on your own doorstep, and it has been really uplifting to see people support us locally. Better education will defeat the peer pressure that has been an issue in close-knit communities in the Dales, especially now that they have been penetrated by outsiders who are more open to new ideas.
"Most of the smaller-scale farmers want to work in a more environmentally friendly way here, but they are hamstrung because dairy and sheep farming has to be subsidised to make a profit. Change is hopefully afoot with new incentives and subsidies.
"Land ownership is the issue. I would like to expand here, but the isn't much availability and it is not cheap."