When your enemy is 3,500 times bigger than you are and wants to be your friend, it isn't always easy to say no.
But when those thoughtful chaps at British American Tobacco called Deborah Arnott to congratulate her on her appointment as director of ASH and to inquire whether she would like to do lunch sometime, the conversation didn't last long.
"I said 'thank you for the call, it's interesting to hear from you, but I don't want to get into this discussion'," says Arnott, 48.
Arnott has problems with the concept of 'engaging', particularly with one of the companies considered by many to be responsible for the deaths of 122,000 people in the UK each year.
"It's ludicrous," she says. "How can a company that's killing half of its customers say it's promoting corporate social responsibility? You can waste an awful lot of time talking and it doesn't get you anywhere."
BAT versus ASH appears to be a mismatch on the scale of Serena Williams versus the British women's number one. The charity, which has an annual income of £400,000, could probably house its five staff in one of the tobacco company's toilets. BAT is worth £14 billion, has 81,000 staff and 300 brands, and still is only number two in the tobacco market to Philip Morris.
Yet ASH has some pretty powerful weapons at its disposal as wave after wave of scientific research lays bare the murderous impact of cigarettes.
They kill six times more people in the UK than accidents, poisoning and overdose, murder and manslaughter, suicide and HIV infection all put together.
"I find it difficult to understand how anyone can work for a tobacco manufacturer," says Arnott. "How can you justify it to yourself?"
Arnott is well qualified to fire the anti-tobacco bullets. She has a background in shaping public policy and journalism. She is also a former smoker. "Oh yes," she confesses. "I was a social smoker in my early twenties.
The most I ever got through was 20 a day."
Far from being embarrassed by her past, Arnott believes it helps her empathise with the majority of smokers who want to give up. While she was still dragging away, Arnott campaigned - successfully - to get cigarettes banned in the workplace at Triumph Cars.
She says 70 per cent of smokers want to quit and ASH is there to help them. That is not quite how Freedom Organisation for the Right to Enjoy Smoking Tobacco views them. Simon Clark, director of Forest, greeted Arnott's appointment with: "Directors of ASH come and go but their message stays the same. There needs to be less hectoring, less lecturing and less reliance on junk science and questionable statistics."
Arnott doesn't like Forest much either. "It tries to portray us as nasty, nanny-state illiberals trying to tell people what to do. But there is a lot of support among smokers for restrictions because they know it helps them give up. Many people say they would find it easier to give up if they weren't tempted to smoke when they went out."
A ban on smoking at work has become ASH's main focus since this year's ban on tobacco advertising. "We know there is public support but we need to mobilise it," says Arnott.
If ASH combined its muscle with Quit and No Smoking Day, the other not-for-profit groups dedicated to getting people off the weed, the message might be more effective. Arnott appears sceptical. The Royal College of Physicians established ASH, or Action on Smoking and Health, in 1971 to educate the public on the dangers of smoking and to give the Government a kick up the backside.
Quit is primarily a smoking cessation helpline and No Smoking Day runs the annual event of the same name. Arnott says Ash will continue to focus on influencing public opinion and political lobbying.
It has had mixed success of late. It congratulated the Government for signing the World Health Organisation's Framework Convention for Tobacco Control, which pledges to "protect everyone from exposure to tobacco smoke".
But it branded the Public Places Charter a failure.
The charter is an attempt by the Government to allow the hospitality industry to regulate itself on smoking, but has led to little more than a spate of signs in pubs telling smokers what they already knew - that it's OK to light up.
By pursuing a workplace ban, which would force pubs and restaurants to outlaw smoking to protect their staff, ASH hopes to eliminate smoking both at work and in public in one swoop.
The workplace ban could become Arnott's big career hit, just as the advertising ban did wonders for her predecessor Clive Bates, who joined the Cabinet Office to the sneers of Clark. "His PR skills were obvious to everyone," he said. "He'd make a great New Labour spin doctor."
Bates, says Arnott, was fortunate to join Ash in 1997 in time to ride New Labour's wave of reforming vim. "There was a period after Labour came in when anything seemed possible, but they have slowed down," she says.
The Government, along with the British Heart Foundation and Cancer Research UK, is one of ASH's major donors. The £170,000 it gets from the Department of Health is loose change compared to the £9.5 billion the tobacco industry delivers in taxes. But as the advertising ban proved, well-directed facts can be more powerful than money. Arnott's aim is about to be tested.