The recent post-16 Dearing review identified the need for students to learn more "key skills" and the Universities and Colleges Admissions Service is working on devising a "point score" for skills-based courses such as the diploma, to enable them to count towards the qualifications needed for a university place. The diploma was highlighted as an example in the Dearing review.
Mr Lewis says the idea came up during a conversation with the chairman of Tesco's, Sir Ian MacLaurin, who employs many graduates.
"He said they were pretty well a dead loss for the first few years because they hadn't learnt to communicate properly, couldn't write a report or stand up and make a presentation," says Mr Lewis.
He applied his mind to the problem and came up with a very practical - and entertaining - skills-based course designed for 16- to 18-year-olds, to run alongside A-levels or GNVQs.
The Diploma of Achievement is different from General Studies in that the emphasis is on skills rather than academic learning. The course is based around four main skills: communication, numeracy, computing and interpersonal skills.
Ideally it is designed to equip students with the skills they will need at university - and then later, in the world of work. So, for example, under "computing" they learn how to set out a spreadsheet and use a word processor; under "interpersonal skills" they learn about team work, and how to make a presentation and write out a report.
The diploma is accredited by the Oxford and Cambridge Examination and Assessment Council, and Lloyds Bank has also sponsored Filofax-type books for students of the diploma, crammed with such varied information as how to open a bank account and how to repair a leaking tap.
The course takes up four periods a week. Teachers and students decide what they will study, from a range of individual units.
Under the topic heading of "health" for example, there are sections on smoking, alcohol, drugs, human sexuality, contraception, sexually transmitted diseases and depression.
The project team, headed by Mr Lewis, spent more than four years researching this material - and consulted more than 120 outside experts. For example, on the unit on "ethics" one topic up for discussion is "The Meaning of Life". "Cardinal Hume wrote a piece for us under that heading in order to get students debating the issue," says Mr Lewis. After each topic had been identified, the project team assembled the most eminent people in that field, who met over a meal to discuss what should be included.
Most of the coursework is designed around activities for students, as well as classroom-based discussions. The emphasis is on the practical. Under "numeracy", managing money is one of the units: how to open a student bank account and work out a budget.
"We also want to make it fun, so under the 'survival' topic, as well as first aid for the body we have first aid for the stomach: how to cook on one ring in a bedsit at university or college. And there's a piece on 'cooking for seduction' - mainly, how easy it is to cook a chicken Kiev, and the value of two candles," says Mr Lewis. "Under 'presentation skills' we also look at the importance of body language - and there are units on basic car maintenance, and what to look out for when you're renting a flat."
Students are assessed on each unit by their teacher as the course goes along. Marks are graded from two to six depending on the level of skills gained, and students who are successful are awarded the diploma with a pass, merit or distinction.
King's College in Worcester, an independent co-educational school, was one of the first to run the project.
"We started off three years ago with a small group of sixth-formers," says Tim Hickson, the second master. "We expected around 15 students to apply, and we had over 60. Now all our lower sixth take the diploma.
"We've found it really useful in terms of developing skills. But it is very different from the rest of the A-level course work - and I think staff with more academic backgrounds do find the diploma hard to teach at first - because it's so much about letting the students demonstrate their skills, rather than standing at the front of the class and imparting your knowledge."
Seventeen-year-old Grant Strover has been taking the diploma course for a year, alongside his three A-levels. "I think it's been great," he says. "We've looked at things we'd never normally look at in school - like how to cook, and how much it's going to cost you to live at university.
"What's stuck in my mind is the team-building - two weeks ago we had to build a newspaper tower with lights that flash on the top - and it taught you how to get your ideas across, and to listen to other people, as well. Usually in lessons you're sitting on your own, not involved with other people."
UCAS forms now carry a section for students to show that they've taken courses like the diploma, and this year one university, the University of West England, has accepted it as part of a student's points score.
This summer a number of further education colleges have been running condensed six-week courses prior to entrance at age 16 using the diploma, and six prisons for young offenders are also using the material. Says Mr Lewis: "I think it's taking off so well because it meets the current gap in key skills among young people that industry is crying out for - and it's great fun to teach and study"nReuse content