The former banker advertising his green conversion

Peter Myers remembers his environmental epiphany very clearly. As a corporate financier working in the frenzied atmosphere of the City in the late 1990s he was responsible for a £100m portfolio of loans on behalf of his employer, a company in the NatWest group.

He had been asked to analyse the impact of new green regulations on some of the bank's biggest clients, customers who included the oil giant BP. "I realised then that what the bank was concerned about was growing ever faster and that this was going to destroy the planet," he said. Deciding it was time to act, he put the question to the chief executive at the time, Derek Wanless, during the filming of a "meet-the-staff" promotional video to mark the bank's annual celebration of its outsize profits.

"I asked him where the future was in a system that worshipped the goal of infinite profits based on the finite resources of the planet," he said. Mr Myers' future as a career capitalist was to take a dramatic turn for the worse.

Mr Wanless, who told his upstart employee that sustainable banking was all about striking the right balance, was soon to depart the firm after a bitter boardroom battle. His £3m pay-off prompted a fat-cat row and in 2002 Mr Wanless wrote a major report for the Government on the future of the National Health Service. Mr Myers took a different path. He decided to put his environmental principles into practice and answered a Greenpeace job advertisement and ended up working there for five years.

Today, having left the campaign group, he is the mastermind behind Enoughsenough.org and responsible for the acclaimed advertising campaign against the huge growth in aviation, the fastest rising source of greenhouse gases.

Along with Joshua Blackburn, of the advertising agency Provokateur, they have invented the fictitious industry lobby group Spurt, headed by Sir Montgomery Cecil who campaigns under the slogan, "Sod them, let's fly". Sir Monty made his third appearance in the national press this week when Enoughsenough, backed by Greenpeace and Airportwatch, took out double-page ads in the national press once more lampooning what they say is the aviation industry's - and the Government's - cynical attitude to the threat of global warming.

Under the headline: "Flying: Your Patriotic Duty", Sir Monty rages: "I am bored of the 'tofu mafia' and their climate change hysterics... I didn't fight in two world wars to see communist liberals tell me, or my shareholders, what to do."

The ad features a link to a Spurt website where an actor playing Sir Monty can be seen tying an environmentalist to a tree and taping his mouth shut. The ads, which have prompted complaints by the industry, have further fuelled the debate over the huge increase in aviation and raised the profile of the campaign out of all proportion to the £100,000 spent on the campaign in the past year.

Mr Myers is reluctant to step into the spotlight - he says he doesn't want to be an "eco-ego". However, he is forthcoming about the need to get the message across.

"It has now been established beyond doubt that climate change is caused by humans - no other issue has been the subject of so much scientific study and consensus.

"One of the most significant things that you can do is cut down on your flying," said Mr Myers, who limits himself to a single flight a year which he triple carbon offsets to combat the pernicious effect of the greenhouse gases emitted by planes. He hopes that Enoughsenough will continue to punch above its weight.

Recent ads have attracted in excess of 50,000 hits to the website and enough donations to keep the campaign rolling, he says. There are no firm plans for the future, only to keep waging an "opportunistic" campaign against the aviation industry and the Government and attitudes to flying like those held by Sir Monty, who asks in the most recent ad: "Why stop doing something you enjoy because the world might be in perilous danger and tens of millions might die?"