On the one hand, she likes technology and speed and relishes going out on her Honda CBR 600 motorbike in her matching red, black and white outfit. On the other hand, she loves pedal power too: she cycles to work, dislikes the motor industry and the influence it has on government and has become the increasingly high-profile leader of a vehement campaign for a change in the law to protect cyclists.
On the day I meet her, in a cafe in Edinburgh on the edge of a road that thunders with thousands of cars and very few cyclists, the UK Government has just announced £94 million for new cycle lanes in English cities and I ask if she thinks the Scottish Government is investing enough in cycling.
She scoffs at that idea and singles out the £500,000 it is spending on a campaign to encourage drivers and cyclists to show mutual respect. "When you're dealing with cyclists suffering serious injuries on the road," she says, "to tell people to be nice to each other is just insulting."
Mitchell's solution is to change the law and introduce a system of strict liability, an idea which she has been pursuing as the leader of the Road Sense campaign group. The change to the law would mean that, in the event of an accident involving a car driver and a cyclist, the driver would be assumed to be at fault unless proved otherwise. Mitchell says reforming the law in this way would bring Scotland into line with Europe but the idea has irritated drivers, lawyers and the Scottish Government.
I have to admit I'm struggling with it a bit myself. First question: shouldn't we all be treated equally under the law whether we're a cyclist or a motorist, and wouldn't strict liability damage that equality? Mitchell's answer is that you have to be realistic about what the roads are really like.
"To say there's equality, ask yourself when you share the roads: is there really?" she says. "Because no matter how hard a cyclist hits a car, those inside the car will not be injured but the same cannot be said of the cyclist. So I don't think we have equality and the law is not saying that suddenly motorists are going to have a really bad time of it." She also points out that, should the cyclist be at fault, damages would be reduced.
OK, second question: wouldn't strict liability encourage cyclists to sue drivers; wouldn't it just fuel the so-called compensation culture? Mitchell gets a bit irritated at that one. She has worked as a personal injury solicitor for 26 years, first for trade unions, latterly for cyclists and motorcyclists, and believes the idea of a compensation culture is grossly exaggerated.
"The idea that people would be more likely to be sued under strict liability is strange," she says. "You cannot be sued unless you've been involved in a collision and someone has been injured so if drivers become more safe and more aware, there will be fewer accidents on the road."
This is a key point for Mitchell. Her main aim, she says, is to make cycling less dangerous and cyclists less vulnerable. She has been a serious cyclist herself for around 20 years, first on mountain bikes, then on racing bikes even though her first love is still the motorbike. She got her licence when she was 18, much to the shock of her late father, a solid, sensible marine engineer who moved from Orkney to Edinburgh before Mitchell was born. He was a big influence on her and it was he who encouraged her to switch from studying history to law.
She studied law at the University of Aberdeen in the 1980s, although it was strictly a weekday business because at weekends, she was out on her motorbike, sometimes pillion behind a boyfriend, sometimes on her own. It was on one of those trips that she had her closest encounter with death on the road.
"It was 6am and it was a beautiful long sweeping left-hand bend near Culloden," she says. "The sun had just come up and there was a herd of cattle coming across the road but we were on the lean and you can't brake in a situation like that. I remember my boyfriend turning round and mouthing 'I'm sorry' because there was nothing we could do. We had to take our chances and the cows separated and we went through."
After graduating from Aberdeen, Mitchell returned home to Edinburgh to look for a traineeship but found it difficult. "Most of the trainees, either their fathers had been lawyers or they went to the right school, and I was state school and ordinary and from a working-class background," she says. In the end, she found a position with a firm that specialised in trade union work and loved it. There was a campaigning element to the work that seemed to ignite Mitchell and it has ever since.
It was while she was working as a trainee, skint but happily bouncing the odd cheque to get by, that she discovered she was seriously ill. The first signs were a little deafness and balance problems and after going to the doctor she was told she had a brain tumour, known as an acoustic neuroma. It would have to be removed. She remembers before surgery, writing a little sign saying 'please let me keep my hair' which she hung around her neck for the doctors to see. Other than that, she wasn't afraid. "Now I would be afraid of dying," she says, "but not then, it had to be done. You get more fearful as you get older."
Mitchell, who is 50, insists she doesn't allow this fear to stop her getting on her motorbike and tries to do some sort of safety training once a year to ensure she is as safe as possible. She also gave up the motorbike when she had children (she has a grown-up son and daughter) because she didn't want to leave her husband without a wife and her children without a mother.
In other ways, Mitchell's approach to motherhood was fiercely pragmatic and focused. "I'm not proud of the fact I had just a week off work for the birth of my daughter. I took six weeks for my son. I was a junior partner at the time, pregnant, and I kept working right up to the end. I remember finding myself at home with this baby and at work I was positive and in control and knew what I needed to do. We had a live-in nanny and I continued to work." Part of the reason she did this, she says, was because she believes law is still dominated by men and women have to fight for their position. "Women have to work harder in law," she says.
Her own legal career has been dominated by personal injury work, and in recent years she's increasingly specialised in cycling and motorcycling cases. She has an office in Peebles, where she lives, and from there pursues compensation for her client and tolerates no criticism of the profession. She is impatient when I suggest the explosion in whiplash claims has given compensation a bad name.
"Certainly there's been a massive increase in whiplash claims," she says, "but what I'm looking at is something completely different - these are individuals with serious injuries and the law needs to protect them."
She applies the same zeal to her work on the strict liability campaign and believes she will succeed. She acknowledges there's strong resistance, not least from the Scottish Government. It has said there is no robust evidence that strict liability would make a difference. But she's impatient with that approach and says the lobbying power of the motor industry has a lot to do with it.
"I think we're in love with the car in this country still," she says. "And the motoring industry is tremendously powerful and you've had a lot of opposition from them. But what we're saying is that the Europeans have strict liability in place for decades and the sky hasn't fallen in. So what on Earth is wrong with us?"