We were living in Cambridge, so I wrote to them and got a reply saying: "We don't have a job for you at the moment, but why don't you pop by the office?" The first day of the school holidays, I was there. Hermann Hauser, Acorn's founder, was a bit surprised, but he took my letter from the filing cabinet and said: "We've got this new computer; do you think you could write some programs for it?" I said I couldn't afford to buy one because I was only 13, but he said: "Not to worry. Why don't you take this one home and see what you can do?"
I took my trophy home. Nicko was pretty impressed at those early blagging skills, and we spent the evening translating an old computer game called Star Trek into Acorn BASIC. Nicko translated and I did the typing. We debugged it and it worked, so we took the cassette in. We showed the people at Acorn, and they didn't do any work all day, they just sat there playing it. They were pretty happy and said: "You guys can come back." We swapped rights to Star Trek for 16K of memory. A lawyer would tell us we shouldn't have settled for less than pounds 10,000 but we were more interested in doing something with the chips.
I didn't become commercial till I left school. But I did buy a broken record player for a fiver from a jumble sale, and discovered I could buy a valve for 82p that would make it work. I realised the electronics thing wasn't as hard as it first appeared.
I was offered a job at Acorn later, and I was so keen I flunked my A- levels. I spent a couple of years on the full-time payroll then moved to London as a freelance consultant. I began developing teleprompters for Autocue, and Nicko worked for me in his gap year before going to Cambridge. We were just having a good time and enjoying finding out more. Then I was commissioned to write a series of books when I was 19 or 20. I don't think we perceived ourselves as being on the leading edge so much as having fun. Acorn had made a new processor chip, and we decided to make this upgrade - which makes a computer run five times faster - before Acorn could develop it. It was guerrilla tactics; we went straight to the manufacturers. We sold the upgrade for pounds 600, a massive sum then. My father has a bio- feedback business, Aleph One, and we've always been in a household where a business was running, so we've soaked up how it works.
Then Nicko thought of developing encryption products. He had been working in web browser technology and doing set-top boxes, connecting TVs to the Internet. A number of things started to come up - the lack of availability of good cryptography systems in Europe, and performance issues. The systems were extremely slow; when there were only 200,000 people on the Internet it wasn't a problem, but as the number grew rapidly, we saw it would be a good idea to start a company.
We came up with an idea because we knew money was available. Nicko had been approached by a Canadian venture capital firm, Celtic House, which said: "If you have any great ideas, come and tell us and we'll think about funding them." In 1995, we took a gamble that the idea would be good enough to be worth the pounds 1m Celtic House gave us. Since 1998, we've sold more than $5m of product. Nicko says I'm a workaholic, but what he means is I don't stop working. That's what I do and I like it. One good thing about working with my brother is that he's happy to take my calls at unreasonable times.We now have 50 people and offices in Boston, New York and San Mateo. We're quite determined to build a place that's fun to work in - I have no time for hierarchy, and I try to make my secretary a cup of tea as often as she makes me one. There's a myth about start-ups, that you have to kill yourself working 25 hours a day. I don't believe that's productive. We try to hire people smart enough to get their work done in fewer hours.
NICKO VAN SOMEREN: Our father gave us a love of technology and an interest in science. He'd run his own business since 1971, so we get some of our entrepreneurial spirit from him. We were always exposed to business, being paid tuppence by Dad to stick labels on envelopes. You're never off-duty. You have to be fairly relaxed but when the phone rings at 10pm, we would always answer: "Aleph One." On my American mother's side, there's a trading heritage too - they built a successful empire in the US.
Alex and I had the usual squabbles, but our relationship improved when he went to boarding school. On some levels, we're similar, though we have different tastes in music: he's into techno, I'm into rock.
My father subscribed to Scientific American, and I remember in 1979, when I was 12, reading an article about public key encryption systems, which is what e-commerce security is founded on. I found the concept fascinating, and spent days studying this article, trying to understand how it worked. It was the kind of maths you don't learn till you're at university. I had a programmable calculator, and finally worked out enough to write a system for it.
During holidays, we worked for Acorn. From that, we got a deep technical understanding, and became used to dealing with people in the industry. By the time Alex left school in 1982, he had an address book of the names of some of the most influential people in the computer industry. We showed up at Acorn for fun, but usually got to take our pick of the books off the technical bookshelf as a reward.
I read computer science at Cambridge, and spent holidays teaching people programming, and looking for bugs in operating systems for Acorn. When I left, I worked for a software company which was bought by the Atari Research Centre. It was a radical shift in culture and I decided not to stay. I was offered a place to do a PhD, so I spent four years working on digital TV image manipulation.
I'd been approached by a venture capitalist. When Alex and I began to develop encryption, he told us to draw up a business plan. So we took an expedition to San Francisco for a data security conference, and cased the joint to see what everyone was doing. People were providing tool-kits for cryptography, but there was a need to solve performance problems for e-commerce.
We have complementary skills; Alex tends to absorb information and gets a high-level view. He's good at strategic planning and organising people, and at sales and negotiating. He does the business side of things and I tend to be deeply technical.
We talk on the phone when we're not together. We have disagreements, but because he's my brother, if I believe he's wrong, I'll tell him. We have the same sense of humour and both make bad puns. The symbiosis is pretty complete. Our investors saw they were getting two brains for the price of one.