This is not going to make much sense to readers of the Driving section. It doesn’t make much sense to me, and I’m the one it happened to: one minute I was a capable driver, the next a feeble wretch unable to use motorways, rendered weak-kneed and trembling by the thought of an A road. Eventually even a short overpass became a heart-thumping ordeal to be avoided by way of lengthy detours and devious excuses.

It sounds silly, but there is nothing remotely flippant about taking 90 minutes to complete a 30-minute journey, burrowing through London’s back streets to avoid anything resembling a fast, straight road. And it’s not easy to explain: sorry I’m late, just thought I’d drive all round the houses for an hour on the way here. You see, I don’t do big roads. They make my palms sweat and my heart pound. They make me panic.

It’s bonkers and it has been going on for seven years, ever since one bright Sunday morning when I was driving home to London and felt a strange reaction to the sign for the M4. I was loath to turn onto the motorway. There was little traffic about, but I told myself the A4 would be more pleasant. It was the beginning of years of self-deception.

I kept passing signs for the parallel M4. Each time I persuaded myself I was better off where I was, despite increasingly heavy traffic. Eventually I could fudge it no longer. I turned onto the motorway and within minutes came to the M25 intersection. I can’t explain what happened next. I was in the middle of six lanes of screaming metal and I could hardly breathe for fright. There seemed to be cars whizzing past on both sides. My hands were slippery on the wheel and I thought my heart might burst. All my instincts told me to slam on the brakes and get the hell out of that car.

Luckily for any number of people, reason prevailed. I drove on, concentrating just on steering straight and breathing deeply. Ah, so this is a panic attack, I remember thinking. And it is fear of a repeat performance that has kept me off fast roads ever since.

I’ve been reduced to pottering about locally. My sister called me a scaredy cat. My husband was exasperated. A few kind girlfriends said nothing, content to do the out-of-town driving; others assumed I was joking, or exaggerating. But I soon learnt that motorway phobia is not uncommon. It strikes men and women, old and young, bad drivers and good. For thousands of once-confident motorists it makes life a misery.

It was when I got lost on Bodmin Moor in mist rather than take a main road that I finally admitted I needed help, and that is how I found my saviour.

Clive Greenaway is a driving instructor. It’s what he wanted to be when he took his first lesson at 17. Thirty years later it’s still what he wants to be. He has every driving licence going: steamrollers, tanks, motorbikes, all lorries, all coaches. He’s also a bit of a driving star: he’s taught Celebrity Driving School.

We stood on a bridge over the M4 for the photographer. I couldn’t go near the edge — just the noise made me dizzy. Greenaway ignored my growing panic and pointed out a feeder lane below where drivers were speeding up and slotting in. I looked. As soon as I focused on what was happening down there I saw normal people behaving rationally, rather than an onslaught of noise and speed. What’s to be so terrified of?

Then I had to drive Greenaway towards the motorway. His presence was reassuring. I knew, of course, that the car had dual controls, but logic doesn’t come into this. For the first time in seven years I found myself turning onto a motorway approach road without feeling trapped, claustrophobic or fearful.

I looked in my mirror — Greenaway told me off for not looking over my shoulder. There was quite a big gap in the traffic and I speeded up to slot in, just like the people I’d seen from the bridge. I grinned. Greenaway congratulated me, in a low-key way. For a while I stayed in the left lane, but soon we drove up behind a lorry on a hill. I waited until there was a big gap, looked over my shoulder and pulled into the middle lane, past the lorry and back into the left lane. I felt increasingly relaxed. We drove into a service station and out again.

Greenaway encouraged me to talk, to say what I was thinking and feeling, so I asked about speed. I was driving at 60mph — when would I have to speed it up? Never, he said. It’s okay to drive at 60. This was a revelation.

I realised that for years I had felt under pressure on main roads to keep up the pace. I had forgotten that it isn’t compulsory to drive fast. I repeated it to myself like a mantra, “Stay at 60, stay at 60”, and as I did so I felt calm.

That was the turning point. I might not have been on the road to Damascus — junction 9 of the M4 more like — but the epiphany was no less vivid. I suddenly realised that just because I was on a motorway and just because cars were tearing along it in the outside lane, I was perfectly entitled to drive at my own pace. That is to say, slowly. I felt liberated of the need to go fast. What I’ve learnt is that I can do it my way, that there’s no need to feel pressured by other drivers. It’s early days, and I’ll probably take another motorway lesson, but it may be as simple as that. Why did I wait seven years?

Growing fear on the crowded lanes

Thousands of drivers in Britain, especially women, suffer from motorway phobia. Many, like Cally Law, fear their reactions are just not quick enough to cope with dangerous situations.

This is not necessarily irrational. Driving at 70mph your car covers 100ft every second. The British School of Motoring — part of the RAC — says it is aware of the problem and is currently debating whether to recommend that the Driving Standards Agency makes motorway driving skills part of the learner test.

The DSA says there are at present no plans to do so.

According to the Association of British Drivers (ABD), a lobby group representing the interests of drivers, rising traffic levels mean more people are becoming scared of joining the throng. “It is a combination of underconfidence in their own driving skills and the increased traffic,” says Tony Vickers of the ABD.

“The more traffic, the more aggressive drivers become, leading to the perception by timid drivers that motorways are aggressive and dangerous. The irony is that in fact they are much safer than many A roads that these drivers will use as the alternative.”