I can still recall not just the teacher who changed my life but also the moment it happened.
Mrs Roberts was a new French teacher at Evington Hall Roman Catholic Girls' Grammar School in Leicestershire when I started my O-levels. Until that point, I'd failed every single French exam and was coasting along.
After her very first lesson she asked me to stay behind. She said: "I'm a bit puzzled by you as I think you're a really bright girl and I can't understand why you're failing French. I just wonder if you're putting much effort in. Do you understand what you need to be doing?"
It sounds mad, but until that moment I hadn't made the connection between hard work and results. I was the kind of kid who was good at what I liked doing - such as maths and English - but made no effort with the things I didn't like or found difficult. If I didn't think I'd be able to do something, I wouldn't even try.
I'd been underperforming for years in French and it hadn't occurred to me to learn any vocabulary. Some of the teaching was a bit casual and that's how I got away with it.
I had always been a mixture of studious and naughty. Once, I locked the German teacher in the stationery cupboard, although I have no idea why. I must have been told off as I broke his glasses ramming him in.
Mrs Roberts transformed my attitude to learning and gave me the tap of encouragement I needed. So, over the Christmas holidays, I put a bit of effort in - the equivalent of five years of effort.
She told me that if I didn't know something, such as a certain word in French, I should make a sensible guess, rather than leave a gap. I remember that my mock French O-level translation involved a bird singing, but I couldn't remember the word for "bird" so I substituted it with "chicken". It made for a rather comical translation, but Mrs Roberts read it out to the class and said this is exactly what you should do. Amazingly, I passed and I then extended my new attitude to every subject.
I ended up doing French A-level and I got an A. I was the only student in the school to get three As at A-level and it was all down to that one conversation.
I can honestly say that if it weren't for Mrs Roberts, I wouldn't have had the career I've had. She helped me to understand that you can become good at stuff you don't like just by breaking down the learning into bite-sized pieces. I always thought I couldn't run a couple of hundred yards, but eight or nine years ago, I built up my running and eventually completed a marathon.
Mrs Roberts taught me confidence and how to be brave - she taught me about having belief in myself and having the courage to ask questions. I've applied that to everything, whether it's doing something dangerous with the Army Reserve or studying an academic paper.
She also encouraged me to make a stab at things. So it is thanks to her that throughout my life I've said yes more than I've said no.
I lost touch with Mrs Roberts when I left school. But when I got married [to television presenter Keith Chegwin in 1982] at the church of Little Stretton in Leicestershire, Mrs Roberts was the first person I saw when I got out of the car. I was really touched that she'd come to see me and I told her what an impact she'd had on my life. I have a lot to thank her for.
Maggie Philbin was talking to Kate Bohdanowicz. She is the co-founder of TeenTech, a not-for-profit organisation that runs events across the country to inspire 12- to 14-year-olds about Stem (science, technology, engineering and maths) subjects.
Born 23 June 1955, Manchester
Education Evington Hall Roman Catholic Girls' Grammar School, Leicestershire; University of Manchester
Career Television and radio presenter for shows including Tomorrow's World, Multi-Coloured Swap Shop and BBC News; co-founder of TeenTech in 2008