The survey by the eight training and enterprise councils for greater London coincides with a blistering attack by 14 leading academics on national vocational qualifications.
The 14 issued a joint statement in the Financial Times criticising Gordon Beaumont for pulling his punches in his NVQ report.
They called the exercise to improve the workplace qualifications "misconceived" saying the assessment strategy was wrong.
The Confederation of British Industry this week called for six core skills, communication, teamwork, numeracy, problem-solving, information technology and self-analysis, to be included in all education and training for 16 to 19s.
Dominic Cadbury, CBI chairman, said: "Anything less jeopardises the chances of young people finding employment." The CBI called for a single 16-19 qualifications framework.