The only remedy is to train a well-drilled army of adult basic skills tutors. And that needs money. The National Institute of Adult Continuing Education says that pound;50 million extra is needed from the Comprehensive Spending Review. But even this sum will be of little benefit if tutors fail to take the jobs and managers fail to train those who do take posts.
The findings of the joint TESNiace survey for Adult Learners' Week, therefore, make depressing reading: three-quarters of colleges struggle to provide lessons because they lack suitably-trained staff. Too much tutor training is viewed as second rate by staff who feel they lack parity of esteem with "real" subject teachers.
This should not be. There is already a wealth of excellent practice to draw on, as the 16-page TES special report on adult numeracy reveals this week. Much of it comes from the initiative of a government which has spent more than any other on adult education in decades.
But, however much effort is put in at the supply end of the chain, it is useless if the 7 million adults identified as having basic skills needs fail to sign up. A disturbing study to be published by Niace next week shows that participation in adult education is at its lowest (19 per cent) since the Labour Government came to power.
Some serious rethinking is needed. While the Government promises free basic skills entitlements to the lowest-achieving adults, the cost of this will have to come from more advanced courses. So why not switch adult tutors to new basic tasks? But then who would be left to teach the more advanced courses?
The Skills for Life strategy that has created so many basic skills opportunities needs another fillip - cash and a concerted campaign to boost training and esteem. A good starting point would be the skills minister Ivan Lewis's suggestion of a skills audit of the entire workforce, to root out hidden teaching talent.