Lang Banks will never forget the winter of 1981, when his household of six became 16.

The director of WWF Scotland was eight and lived with his brother, two sisters, Scottish father Bob and Vietnamese mother Minh in a villa in West Kilbride, Ayrshire.

It was a bitterly cold winter and into the midst of it, Banks' aunts, uncles and cousins arrived, fleeing communist Vietnam. For the next year all 10 lived with the Banks family, with the new arrivals sleeping one family to one room.

"It is burned on my memory," says Banks, with a laugh. "I don't think I really understood it as a kid. Suddenly there were all these extra people in your house who didn't speak the same language as you. All your possessions – your toys and clothes – were shared, because they didn't have any.

"In typical Asian style, food was cooking in the kitchen constantly, morning, noon and night. The house was big enough to accommodate us all but it felt overwhelming."

Soon enough the newcomers found their feet and homes of their own, but the experience made a huge impression on Banks. Though it had its tough moments, it was a reminder of the big, wide world out there beyond the Firth of Clyde. That, coupled with his own heritage, has made him "definitely an internationalist".

So it's no surprise one of his top priorities as WWF Scotland's new director is to push for Scotland to use its influence in the wider world. "The priority areas are marine, climate, energy and fisheries," he says enthusiastically.

Banks, 39, took on his new job in January, having been a communications manager for many years, running media campaigns first for Friends of the Earth (FoE) Scotland and then WWF Scotland. His campaigning began at university in Paisley, when he ran the environment group while studying for a biology degree, and he has been at the heart of most major environmental campaigns of the past 15 years (at one point, working for FoE, he even ran a campaign targeting WWF, over its partnership with Lafarge, the aggregate company that wanted to open a superquarry on Harris).

Green issues are not exactly making headlines these days. David Cameron's husky sled ride in 2006 now seems like a scene from a dated political satire, international talks on climate change have stalled and campaigners are deeply concerned the very first greenhouse gas emission reduction target linked to Scotland's much shown-off Climate Change Act has been missed.

Banks, however, is an optimist – "I don't think you can do a job like this if you're not" – and believes that with the political will, Scotland can still meet its future targets.

Chatting over coffee in an Edinburgh cafe, he is full of his customary cheerfulness, which he retains later when standing in the rain being photographed. How does it feel to be in front of the camera instead of holding the flash out of shot as he used to do as a press manager? "It's actually a bit weird," he admits, breaking into a grin just as the flashbulb flares.

While Banks's outlook is international, his interest in the environment is rooted very much in Scotland. Not only did he wake up each morning as a child looking out to Arran, but his boyhood holidays in Argyll were the stuff of Gerald Durrell stories. For over a decade, summer meant going to a croft in Argyll. "We'd drive up, the car stuffed to almost bursting with the cat stretched out across the dashboard. I'd look for beasties in the streams, chase burnet moths across the hills or lie watching the buzzards for hours. You made your own fun – finding caterpillar hawk moths and feeding them, or building a bonfire."

As he got older, there were often long, passionate discussions over dinner which would turn to world affairs and history. "My dad was very political with a small 'p' and he could draw upon all these moments in history to inform his views." Bob Banks came from a working-class family in Old Kilpatrick and trained as an engineer before emigrating to Canada. There he joined Canadian External Affairs, which took him to Saigon – now Ho Chi Minh City – as part of a peacekeeping mission in 1965 where he met Banks's mother Minh who came from a family of goldsmiths in north Vietnam.

Minh and her mother and siblings had fled the south following the defeat of French forces by Viet Minh communists in 1954 and when Bob Banks met her she was working at the United Services Organisation as secretary to the director. The couple married and on their return to Scotland settled in West Kilbride where Bob had been evacuated after the Clydebank blitz of 1941.

Minh was dubbed the "first Vietnamese person to come to live in Scotland" by newspapers. A social work assistant and seamstress, she threw herself into community life. Sadly, Banks lost both his parents in the last three years, Bob, aged 79, in May, 2010, and Minh, aged 66, in November, 2011. "It's such a shame that after looking after my dad for so long my mother didn't get to live and enjoy retirement to its full extent."

Although he has worked for only two environmental organisations, they occupy distinctly different niches, FoE on the outside, always snapping at the heels of government and business, while WWF has a programme of collaboration with business. Its partnership with Lafarge at the time of the Harris superquarry dispute, which ended in 2004, was bound to put it at odds with FoE. "WWF Scotland throughout were always very clear that they didn't support the project either and they were furiously lobbying the company from the inside," stresses Banks.

Did he buy that argument at the time? "I probably didn't because I didn't know the organisation then or the people in it. But my boss, Kevin Dunion, and the head of WWF weren't falling out about it. WWF knew it was actually very useful to have that extra voice."

With hindsight, how effective was WWF's voice in dealing with Lafarge, which eventually dropped its plans? "I think it was pretty critical, actually." Somebody needs to prod industries along in the right direction, he insists. "I'm not going to say every partnership [with industry] has worked as well as WWF would have liked, but the good thing is WWF can also end those partnerships and has done." With groups like FoE and Greenpeace on one side, and WWF on the other, he reflects, campaigners can catch their targets in a pincer movement. Which brings us back to the Scottish Government's failure to meet its emissions reduction targets. Banks sighs. "Politicians are very big on voluntary measures," he says, "but there needs to be a cut-off."

Where voluntary measures fail, legislation should follow. WWF is pushing for the Scottish Government to introduce minimum energy standards in people's homes, to help reduce fuel use and fuel poverty, but is frustrated ministers are dragging their feet.

There is much to do, then, which doesn't leave Banks with a lot of free time. Plans to pick up Spanish again are on hold, but he is determined not to return to his working patterns at FoE when he practically lived at the office. So far, he is getting away at a reasonable time to see his wife in their Perth home, which they share with two cats and several chickens: "There's nothing more therapeutic than coming home at the end of the day and watching your chickens wander around."

He is big on trying to reduce his own carbon footprint, with plans, after his hand-me-down car has gasped its last, to get one that runs on chip fat. He has a solar water heater on the roof and is looking at getting extra membrane insulation to put on the inside of the house's solid walls. He even reads the gas and electricity meters every weekend, he admits, sounding slightly embarrassed, and yes, there is a spreadsheet.

Such small steps make a difference, but for change on a large scale, it requires Government action, which is why he wants supporters to keep up pressure on the Scottish Government. To ministers, his message is simple: "Make it possible for me to keep talking with pride globally about the great environmental targets Scotland has set itself, by actually delivering on them."

Lang Banks

Director of WWF Scotland

Picture: Gordon Terris