The engineering gap
When Dawn Bonfield, the former chief executive of the Women's Engineering Society, ran a stand recently at a big military airshow, she was in for a shock.
There were around 900 Brownies amongst the crowd and Ms Bonfield recounts, "I'm saying to all these girls, 'Do you know about engineering, would you like to be an engineer, have you thought about engineering?'
"And in the whole day... probably five or six of them said yes. Every other one said no, just straight out no."
What surprised her most, she says, is that it wasn't that these eight and nine-year-old girls didn't know what engineering was. Simply that they had already switched off.
"So how much work does it take to change that?" asks Ms Bonfield. "I mean it's huge."
There's no shortage of data to back up her estimation of the scale of work required. The latest figures from the Office for National Statistics show that women make up around just 8% of engineers in the UK.
And this is at a time when the UK needs to produce thousands more engineers, so much so that the inventor, Sir James Dyson, is planning to open his own institute to address the skills shortage.
Further back in the chain that links school, university and then employment, other data show that 49% of state schools send no girls to study A-level physics. And of those students who are taking an A-level in the subject, only a fifth are girls - despite getting similar grades at GCSE as boys.
At the John Warner School in Hertfordshire, where you can take a GCSE in engineering, Dawn Bonfield's discoveries would come as no surprise to the girls in the GCSE and A-level groups. They are well aware of the stigma surrounding women and engineering. It seems even in the 21st Century it is still thought of as a job for a man.
"It starts at a young age... and that's just what we've grown up with," says Sophie, who did an engineering GCSE, but isn't continuing it to A-level, because of a timetable clash.
She puts it down partly to the fact that "girls are just put in the corner with a doll" - while boys play with trucks and cars - and partly down to the idea that manual labour is the preserve of men.
"It's only when you get to GCSE age that that option's offered to you, so a lot of people might still at that age be thinking, 'Oh well, I shouldn't be doing building or coding,' and stuff like that."
The girls at the John Warner School seem to defy some of these perceptions - 11 out of 13 of them said they would consider a career as an engineer. Nevertheless all of them are vastly outnumbered by boys in their different GCSE and A-level classes in engineering. And they're in the minority in physics and maths classes too.
Mum and dad matter
Sexual stereotyping and not enough female role models are well documented as reasons why girls don't choose engineering. As are misconceptions about the job itself, which isn't always about getting your hands dirty.
Campaigns such as the Institution of Engineering and Technology's "#9PercentIsNotEnough" are trying to address this.