When its producers decided that the series should reflect the trend of the past 10 years for pupils with disabilities to be educated at mainstream schools, Carol Carton, a former support teacher at Francesca's school - Parliament Hill girls' comprehensive in north London - introduced her to Grange Hill's producer, Christine Secombe.
Francesca, who suffers from a lack of physical co-ordination, 'stood out from the beginning', says Ms Secombe. 'She was a delight to talk to and had both humour and maturity. During an audition she succeeded in making us laugh at a particular scene we had watched about 20 times - she was able to bring something extra to it, which is a sign of real talent.'
Since Francesca landed the part, after two auditions towards the end of 1992, she has had to miss quite a bit of school to attend rehearsals. Consequently she has needed to work hard to maintain progress towards her GCSEs - not least because Grange Hill has a policy of writing out of the series characters who fall behind at their real schools. 'That is the most difficult part,' Francesca says. 'Sometimes I have to spend all weekend doing homework - but it's worth it.'
She describes her character, Rachel, as kind and thoughtful. 'They are trying to portray me as a normal person who fits in, even though I look different - for example, I beat a boy at a computer game.'
Sometimes the Grange Hill scriptwriters loosely base incidents in the series on the actors' own experiences, and in another scene Rachel is shown having an argument with a PE teacher, who is trying to make her play tennis.
Back at Parliament Hill, Francesca's drama teacher, Juliet Munnelly, is pleased that she has had such an exciting opportunity, although she notes that Francesca's drama is not always that good at school. 'I know Francesca finds acting for real more rewarding,' Ms Munnelly says, 'but the GCSE drama course we do here is based on imagination and creativity. There is no script work, so there is a big difference with what she does at Grange Hill.'
Television aside, there is also the difficult issue for the school of helping a physically disabled pupil to cope with the mainstream educational environment. Francesca is one of a very small number of such children that Parliament Hill has taught, and tensions inevitably arise.
Gill Wilson, head of Francesca's year, says: 'There have been some problems, such as staff not always having the skills or the confidence to cope with all eventualities, and in many respects we don't have ideal facilities. Practical difficulties arose, especially in the early days, such as who would carry her bag.'
Initially some of Francesca's classmates felt that she was being allowed to get away with more than they were - talking in class, for instance. 'We had to stress to her teachers that she had to be treated in exactly the same way as everyone else,' Ms Wilson says. 'After all, there were students in her class who had comparable, albeit not visible, disabilities, and they didn't always receive the extra attention that Francesca did.'
Elizabeth Kitcatt, Francesca's form teacher, echoes those comments: 'It was very difficult, especially to begin with, to make 11- and 12-year-olds understand that Francesca was not getting preferential treatment, but help that would compensate for her disability without giving her an unfair advantage.
'Many of them felt that this was an unfair situation, especially as she was perceived to be academically able. There are students in her class with less ability but who none the less do not get extra help.
'Generally, the issues are far from clear-cut, and at times it has been difficult to implement a policy of equal treatment that has been regarded as fair by everyone.'