The couple encouraging people to release their inner Tarzan

It was seeing people of all ages larking about on a treetop adventure course in rural France 15 years ago that sparked Rebecca and Tristam Mayhew's lightbulb moment.

Mrs Mayhew says: "I turned to Tris and said 'this is what we should do'. We'd never come across anything like this before, nobody was doing this in the UK.

"We thought, 'why wouldn't [British] people love this?'"

Already hungry to leave their office jobs, the couple decided there and then to set up a similar business in the UK.

So returning home after their family holiday in 2001, they handed in their notices, and immediately put the wheels in motion.

Conscious that having people whizzing about treetop zip wires required the highest possible safety standards, the couple first went to the Royal Society for the Prevention of Accidents, which gave them its backing.

Then came the issue of finding the first location for their business, which they named Go Ape.

The couple decided to go to the Forestry Commission to see if they they could build their inaugural adventure course in Thetford Forest Park, on the Norfolk/Suffolk border in eastern England, a location Mr Mayhew had previously visited and was fond of.

Their pitch - which went very well - was that they would pay a basic guaranteed rent, and also hand over a share of any profits.

Mr Mayhew says: "East Anglia [Forestry Commission] were really entrepreneurial, and innovators. They were biting my arm off."

Bankrolled by digging into their savings, and from the sale of a second home, the Mayhews opened their first outdoor adventure park site in Thetford in March 2002.

Demand for zip wiring and tackling treetop obstacles in the outdoors soon took off.

Go Ape now operates 29 sites in locations such as Southampton, Crawley, Leeds Castle and Battersea, London, employing 800 staff during its peak months.

The company, which has its headquarters in Bury St Edmunds, Suffolk, also operates sites in 12 locations in the US through a joint partnership.

Go Ape's financial reports show the business is in shape, with a turnover of £18.7m in the year to 31 December, 2014, following annual growth of 32%. Meanwhile, pre-tax profits for the same 12 months totalled £2.9m.

Yet the growth wasn't all plain sailing. Mr Mayhew has admitted in the past that when starting out, they forgot to account for VAT, and after the opening of one course was delayed due to a planning permission issue, the business found itself financially stretched.

To cover the cash shortfalls at the time, Mr Mayhew said he had to borrow money from his mother, before paying it back two months later.

Part of Go Ape's selling power is its wide appeal - it is deliberately aimed at people of all ages rather than just children.

"Brand awareness is really strong as it appeals to a diverse group of people," says Mrs Mayhew.

"It's fantastic for families, groups of friends, stag parties, corporate groups - actually we take over £1m per year from corporate business."

Analyst Daphne Kasriel-Alexander, a consumer trends consultant at research group Euromonitor International, says Go Ape has benefited from a growing number of people wanting to try new activities in their leisure time.

"Go Ape is doing well in its industry because people want to do something different and get out of their routine," she says. "People are keen on collecting experiences."

On a daily basis the couple, who are both 47, split their responsibilities.

Mr Mayhew is chairman, with his role involving finding new sites and working on new concept designs, while Ms Mayhew oversees the marketing.

Such is the couple's love of the outdoors, that running Go Ape seems a much better life fit for them than their previous jobs. Mr Mayhew formerly had a communications job with US giant General Electric, while Mrs Mayhew was a charity fundraiser.

Mr Mayhew, who jokes that his job title is "chief gorilla", and actually spent 11 years as an officer in the British Army prior to joining the corporate world, is currently training for the Three Peaks Yacht Race.

This sees entrants having to sail from Wales to Scotland, stopping on the way to run to the top of the highest peaks in Wales, England and Scotland - Snowdon, Scafell Pike, and Ben Nevis.

Meanwhile, Mrs Mayhew regularly escapes to the countryside on her mountain bike.

In addition to expanding into the US, the couple also launched a new UK business in 2014 - Air Space, an indoor trampoline park.

Mr Mayhew says: "As our hours tend to be reduced in winter, we thought this could be something we could run that's quite similar to Go Ape."

Air Space now has two locations - in Wolverhampton, West Midlands, and East Kilbride in Scotland - with more outposts planned.

Mr Mayhew says the aim is to keep expanding both businesses.

"We know instinctively that unless we are growing, we are going backwards," he says. "If you're a strong growth story, you attract the best of the best."

With an ambitious strategy that involves opening about five new Go Ape sites both in the UK and US in 2016 alone, the Mayhews are as determined as ever to encourage more people to monkey around in the forest in their spare time.