Here's a simple multiple-choice question for you: two-thirds of boys and half of all girls fail to meet GCSE expectations and are labelled unemployable at the age of 16. Who or what is at fault? a. The feckless teenagers; b. Poor teachers; or c. A system that assesses only narrow academic learning, bears little resemblance to employers' needs and ignores the skills and abilities possessed by the dispossessed.

There is little doubt in the mind of Colin Birchall, chief executive of Pertemps People Development Group, that the answer is C. Mr Birchall's Midlands-based company has, through the Welfare to Work programme, helped more than 60,000 long-term unemployed people into real jobs. Not through gaining more, often pointless, qualifications, but by developing skills and talents such as effective communication, initiative or teamwork, which are invisible to the academic examiner but invaluable to an employer.

So little faith has he in the prevalent methods of assessment, that when recruiting his own staff or helping clients back to work, Mr Birchall refuses to look at CVs, believing that exam grades, or the lack of them, cannot accurately display a candidate's potential. Instead he searches for the individual's spark of brilliance, the one thing that makes people feel worthwhile and good about themselves. That one spark, whether it be a talent in music or sport, gardening or mechanics, is then used as a starting point to build up a sense of accomplishment and self-worth which can be transported into other areas of life and eventually into the workplace.

The search involves a series of role-play and discussion exercises that encourage clients to see how often the skills they use just living their lives can be useful to an employer. "The single parent on a limited budget, bringing up children in a deprived and sometimes threatening area has developed an amazing range of skills that can be honed for the workplace," says Mr Birchall.

There is nothing magic about what Pertemps achieves with those dismissed as failures by an academic and theoretical education; nothing that schools, released from the straitjacket of tests and targets, could not develop with pupils before they are rejected as defective, if only the system were refashioned to take account of every ability, not just the academic.

Schools need the time and space to search for the spark in all pupils, not just those who happen to fit into the narrow band of abilities that are currently examined. But even if we can persuade the powers-that-be to stop weighing the pig, the problem remains how traditionally unqualified teenagers can convince employers fixated with exam grades and addicted to the crude filter of GCSEs and A levels that they are worth interviewing too.

One possibility envisioned by Andy Powell, chief executive of Edge, the education foundation with the ear of ministers, is a multi-media portfolio of achievements that could include video clips of a workplace skill in action, as well as certificates, exam grades and references. As he says children brought up on YouTube and Facebook should have no trouble uploading clips to demonstrate an ability untouched by examiners. Such a document could treat both practical skills and academic success equally and perhaps go some way to bridging the peculiarly British gap between vocational and academic assessment. And, maybe, employers could be weaned off their dependence on an assessment system created for a very different labour market half a century ago.

Such a portfolio, reflecting the broadest achievements of school leavers' abilities, should be allowed to become an entry pass for our marginalised and disenfranchised youth to a more productive future.

Alison Shepherd is a freelance education correspondent and former chair of governors at a north-east London primary school