It was down the front of Kylie Watson’s off-white cotton knickers, on the top deck of the thirty-seven B Route Master from Edmonton. Two quid for a squiz, three for a rummage. I paid one pound-fifty for a quick flash and the memory has stayed with me for life, seared into my brain like a cattle-brand. Now that, I think, is value for money.

It was the moment everything fell into place for me. An epiphany on the road to Dollis Hill – God talking, and I can best express His message with this simple equation: let us say that the value of something to you, or the world at large is X, and in order to possess this thing you are prepared to pay Y, then provided the value of Y is less than X, (x > y or y < x), then you’ve made a return on your investment.

Sion is the author of The Sleepwalker’s Introduction to Flight

You’re in business, chum.

That afternoon I made a plan. The discount carpet warehouse round our way always kept a stack of off-cuts in the yard which were good for nothing much unless you lived in a phone box. Or so they thought.

I bought the lot for a song (Y), got them professionally trimmed and hemmed and then flogged them on to the dealerships as bespoke car mats (X). That’s how I got my start; that was how Peter’s Parts was founded and grew to become the chain of car-accessory megastores that today, stretches all the way from Watford to Wandsworth.

Some of you may know me as Peter the Great – Czar of the Car, from my humorous, high-energy radio and television commercials. But this zany, spontaneous, knockabout public persona is by no means the real Peter Tremlett.

In reality I am a disciplined, considered individual; everything I do is governed by the Dollis Hill doctrine. My life is a constant series of evaluations predicated on the simple principle: is X greater than Y? And if not, why not? I expect my managers to be able to give me a running total of a branch P & L at any time of the day or night.

And believe me, I do check.

So, it may come as no surprise to learn that I’m a wealthy man, which is why some of you might be puzzled to learn that I drive a second-hand ‘R’ registration Mondeo.

But I apply precisely the same principles to my own lifestyle as I do in business. I can afford a Lotus or a Ferrari certainly, but where’s the return on the investment?

Within six months the vehicle would have lost nearly twenty-five per cent of its handbook value. Yes, it might be fun, but the pleasure of driving would by no means compensate for this depressing fact. Every mile I traveled would contribute to the decline of the ‘X’ value. To me a Ferrari Testarossa simply does not conform to the paradigm of Kylie Watson’s knickers.

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Of course, I’d be the first to admit that human beings are not entirely rational entities and Peter Tremlett is no exception; I am a creature of flesh and blood and emotion. If you cut me do I not bleed? If my revenue falls in the third quarter as a result of seasonal market adjustments, do I not shed a tear? But I can prove that the hard logic of my life-formula is applicable even to the abstract equations of relationships.

There are many wonderful people in my life that I am proud to call my friends. Not one of them has ever let me down or betrayed me and how many of us are fortunate enough to be able to say that? It’s no accident though. I’ve selected them wisely and well through judicious application of the equation. Strange as it may seem, my very dearest friend is also my closest competitor: respected entrepreneur, Allan Langstaff owner of Allan’s Auto-parts.

Allan and I meet once a week for dinner; to chat about business and how we might set the world to rights. Allan likes to talk at length and favours the full-bodied vintage reds. The bill is often some three hundred pounds or more, but I don’t regard this as an extravagance or money wasted. It’s an investment like everything else; an investment in fellowship and goodwill.

The return is a pearl beyond price: Allan’s trust. Occasionally, Allan does forget himself and reveals odd snippets of information about his revenues and pricing structure which might be advantageous to a competitor. But I would never abuse this. I would never pass valuable data to a third party.

At this point I feel that it is only fair to warn you, the life-formula is not always an easy thing to live by. I wear my heart on my sleeve and must be constantly vigilant to curb my naturally sensitive nature. There are occasions when I’m tempted to stray from the path and meeting Diana Redhouse was one of these.

Diana and I bumped into each other at one of Allan’s Cheese ‘n’ Pineapple ‘n’ Cabernet Sauvignon evenings and I’ve never come across a finer example of engineering, particularly her flamboyantly cantilevered upper fender arrangement.

It was what I was gawping at in my rear view mirror when we shunted.

Thankfully, it turned out that her classic, nineteen sixty-three Sunbeam Alpine was due for a full bodywork recondition and in any case, the damage was only superficial. If anything, my old Mondeo probably came off worse. We climbed out of our vehicles, swapped numbers and that was that. Or so I thought.

But we got chatting later over the cheddar nibbles and it turns out that Diana Redhouse is the daughter of none other than old John Smedley-Redhouse, designer of the Smedley-Redhouse universal joint, mainstay of the old Austin Healeys. What this woman didn’t know about ball-joint tension frankly wasn’t worth knowing; a woman who kept a Gator-Grip Universal Socket Set and a can of WD40 in her handbag.

So, one thing led to another and I took her out a couple of times. Honestly, I’ve never met anyone so thoroughly immersed in the nitty-gritty of mechanics. On one of our romantic picnics in Hyde Park, I watched open-mouthed as she suddenly leapt to her feet, flagged down the groundsman and proceeded to fine-tune his ailing motor-mower. In Kensington, a passing nanny had the brake cable on her pram swiftly overhauled and re-tensioned. But it was over dinner at Quaglino’s that I knew I was smitten; it was the night she removed, lubricated and aligned the squeaky wheel from the dessert trolley.

Afterwards in the flickering candle-light she reached across and gripped my hands in her oily fingers; delicate filigreed webs of black delineated the skin of her knuckles like cracked varnish. At that moment I loved her. I leaned across the table to plant my lips on hers but the moment was broken by the sound of a car backfiring in the distance. A tiny swallowtail of concern appeared on her brow. I could see that she was considering the problem.

‘Hmm,’ she muttered, ‘they want to enrich the idle mixture by backing off the screws an eighth of a turn or so.’ It was then that I realised how close I’d come to undermining my own doctrine.

These very hands I’d seen only that afternoon, fixing a broken fan-belt in the Fulham Road with one of her own fine-mesh stockings.

What was I doing? What was I thinking of? How could I, Peter the Great, owner of Peter’s Parts, be falling in love with an out-of-control, philanthropic mechanic whose agenda was not the replacement of vehicle parts which are my life’s blood, but the servicing and maintenance of same? I adored her, but Diana and I were philosophically, a universe apart.

And so I flung those hands away from me like twin serpents. I made a quick calculation of all that I’d spent so far in this relationship. Quite a bundle as it turns out. But to be fair, she’d also put her oily hands into her own dungarees in respect of dinner bills. So I reckoned we were about even. And then, she threw a glass of sparkling wine in my face and walked out. Three quid wasted. I finished the rest.

In this instance I don’t resent the fruitless expenditure of three pounds – in any case it may prove to be tax deductible – but we all make mistakes and I don’t think that’s too high a price to pay. Not when you consider that everything else worked with Diana. She just lacked the ‘X’ factor, that’s all.