Many chief executives would have turned on their heels and beaten a hasty retreat if they arrived at work one day to be confronted by a mob of angry protesters waving banners and chanting abusive slogans.
They might at least bolt the doors firmly behind them. But not Jo Williams - she invited them in for tea.
Along with several larger charities representing people with disabilities, Mencap has come under fire from protesters convinced that it and similar organisations are too paternalistic and don't represent the interests of disabled people.
In November, Mencap was one of four organisations targeted by protesters from the Disabled People's Direct Action Network, who cordoned off the charity's London head office with mock police tape and daubed the building in stickers declaring "Fuck off Mencrap". Some of the other charities subjected to similar tactics battened down the hatches and waited inside until the commotion died down. But that simply isn't Williams' style.
"It's quite challenging to be faced with 30-40 people shouting abusive things about the organisation that you feel so committed to," admits Williams.
"But my view is that the only way to make progress is to talk, so I invited them in for tea and biscuits. They stayed for two or three hours and we had a long conversation, some of which was fairly heated. But I hope that by the end of it they felt I had listened - I feel we achieved respect for each other," she says. "The main thing that struck me about them was the sheer intensity of their sense of oppression."
Williams always wanted a job at Mencap. She became interested in working with people with learning disabilities and their families early on, when she was employed as a social worker. Back then, as the driving force behind one of the UK's first community living schemes for adults with learning disabilities, she witnessed the effect of moving people with learning disabilities from institutional to community-based services.
The experience had a lasting impact on her.
"Overnight, I saw people change, grow and develop confidence - the transformation was remarkable," she recalls. "I remember rushing back to my office and telling everyone that one day I wanted to work at Mencap because it made that kind of impact every day. When I finally joined Mencap in 2002, my previous boss was one of the first people to call. He said: 'Do you remember 20 years ago saying that you wanted to work for Mencap?'"
That Williams made it to her dream job would have surprised no one. Despite her bubbly nature, she is a determined character. Focused and driven, there is no going back once she has set herself a target - witness the four marathons she has run since 1996, most recently the 2003 London Marathon in aid of Mencap. She remains committed to an early morning regime of running and gym visits before work.
"I've always enjoyed running - it's a great stress-buster and it keeps me fit and healthy which enables me to be energetic at work," says Williams.
"Of course, some of the qualities that you develop as a runner can also be useful in leadership. I've learned to be fairly single-minded and tenacious when I put my mind to it."
Her main task at the moment is to tackle the causes of the oppression felt so keenly by the protesters, by opening up opportunities for people with learning disabilities and overcoming the discrimination they face.
She has taken a long hard look at her own organisation, as well as stepping up campaigning activities to make other employers more aware.
One of Mencap's 11 trustees, eight of its 150 headoffice staff, and 30-40 per cent of its national assembly members have a learning disability, as has one of the assembly's two co-chairs. And Williams is implementing a five-year plan to increase these figures.
"I want to create opportunities for people with learning disabilities within Mencap, so that they can go on to be role models," says Williams.
Ultimately, Williams hopes to use this ethos to open the way for Mencap to appoint a learning-disabled chief executive, perhaps taking on the role as part of a job-share.
"It is so important to be fully aware of what the world is like for people with learning disabilities, and with a job-share situation, both people would bring different skills and experiences," she says. "The combination could prove to be very beneficial."
As for Williams' own future, she is unsure - after all, what is the next natural step after landing your dream job?
"It is no secret that I have set my sights on staying at Mencap for five years, by which time I hope we will have made some serious inroads into the issues," she says. "I believe that every chief executive really needs to review their position every five years, and I'm no different. When the time comes I'll step back and see how much energy is left in the tank and take things from there, but I wouldn't want to saddle them with me for more than five years at this stage!"
There is one thing, though, that she is clear on: "The team here keep asking me if I'm going to run the marathon again this year. I'm inclined to think that four is quite enough - I don't plan to run another," she says.
Mind you, she said the same thing in back in 2000, before going on to run the 2002 New York and then the 2003 London races.