She succeeds Norma Anne Watson at a time when GTC Scotland is grappling with the review of chartered teachers, a huge influx of probationers and questions over whether the teaching profession should continue to self-regulate. She will need all her vast experience in teaching, management and union activism.
A member of the Educational Institute of Scotland (EIS), which negotiated the national teachers' agreement in 2001, she has taught for 32 years - albeit in only two schools, Yoker and Victoria primaries, both in Glasgow.
Born in Clydebank, Ms Ferries, 54, started teaching in Yoker in 1975, at a time when there was such a teacher shortage that children received a part-time education: half went to school in the mornings, the other half in the afternoons. There were a lot of probationers at the time. "It was sink or swim," she says.
"I had thought I was gifted because I did all my teaching practice in a good school and then got an evaluation of being a good teacher from the college of education. But I landed at Yoker and got systematically devoured on a daily basis," she admits candidly.
When the head wrote on her probation form that she couldn't control her class, it was the catalyst for her involvement in the EIS. At that time, one of the main union campaigns was trying to enforce maximum class sizes of 33 - something that did not endear her to her headteacher.
Her tale took a happier twist, however, when "the dragon" was replaced by a new head - none other than Chris McElroy, now HMIE's chief inspector for the primary sector, whom she likened to Radar in the television series M*A*S*H. "He couldn't have been more different from what we had had before," she says. "He created a climate of involving staff."
At conferences, Mr McElroy sometimes shows a film, demonstrating how to involve early years pupils in language. The teacher is off-camera and all you hear is a calm voice telling a story about the sea, shells and other underwater things, while the children listen intently and explore shapes and textures. That teacher is May Ferries, more than a quarter of a century ago, pioneering child-centred education under Mr McElroy's leadership.
At about that time, the inspectors gave the school an outstanding report for its language development work. It was the trigger for her to fly the nest and go to a new school, Victoria Primary, as its assistant head. Very shortly afterwards, the head moved to another post, so she became acting head - not an experience she enjoyed.
Ms Ferries found running the school an isolating experience. When a member of the public complained that pupils were being left to play outside in the rain - and the education authority backed the complainant against her policy (she argued that there was a large shelter to keep them dry) - she withdrew her application for the permanent post.
Although she has worked as an acting head since then, she has never wanted to move beyond her current role as depute.
Her membership of the GTC spans three four-year terms and has covered all the key areas - probation, teacher development and the accreditation of initial teacher education courses, discipline and exceptional admissions.
But the big challenge she faces will be persuading teachers of the importance of these issues and getting them to "fork out" their pound;40 annual fee.
More of a concern is the potential pressure on the council to reform along similar lines to the General Medical Council. Ms Ferries likens the regulatory issue to the response to the Dunblane massacre, when schools spent "squillions of money on door entry systems".
There are also strong suggestions that the teacher majority on the council should be reversed.
Another fear haunting the council is whether A Curriculum for Excellence will herald "generic" secondary teachers, replacing subject specialists.
She does not believe it will happen, but accepts that cross-curricular work in secondaries is not going to be easy.
"Everyone wants to work together for the benefit of the kids," she says, "but if your job security is based on your ability to hang on to pupils in your department and stop them choosing someone else's, that is quite a high level of professional trust for people to get involved in."