In September 2003, the Crick report recommended that immigrants seeking citizenship should be able to show measurable progress in a UK language as well as a knowledge of the life and civic structures of this country.
At present, refugees and asylum-seekers in receipt of benefit are eligible for free language classes. But other migrants are required to have lived in the UK for three years before they qualify for free ESOL tuition.
Sir Bernard Crick's report recommends that the three-year rule should be abolished and that an entitlement to free courses should be available to all those who enjoy indefinite leave to remain. With some 120,000 immigrants a year being granted that entitlement, many more people would be entitled to free language classes.
"I think scrapping the three-year rule is extremely important because people get stuck in a monoglot employment situation right from the beginning - unless their English is good enough to work in an English-speaking environment," Sir Bernard said.
"This has knock-on effects for integration, race relations and community cohesion."
On the other hand, he concedes that if free classes for everyone were introduced all at once, then there would be long waiting lists for tuition as there are not enough ESOL teachers in the UK.
There are an estimated 5,000 ESOL teachers in England, but Sir Bernard predicts that many more will have to be trained in the next two or three years.
Immigrants, he added, should be offered at least the same minimum educational opportunities as other British children - in other words, the ability to speak English and some conception of where they are living.
The Government has agreed that for migrants to become British citizens they should be able to show that they have made progress from one ESOL level to the next, with an underpinning minimum standard of ESOL entry level one.
They must also have some knowledge of the UK and its political structure and have lived in the country for at least five years.
But the Government has not yet agreed to abolish the three-year residency rule regarding the entitlement to free English language tuition. The Home Office says that abolition would considerably increase the number of people eligible for free courses, and therefore the expense to the state.
Irene Austin, co-chair of the National Association of Teachers of English and Community Languages, and curriculum manager of adult and community learning at Oaklands college, said: "People working from countries outside the EU need to be here for three years to gain free access to tuition.
"Our main concern is that people do not have immediate access to these programmes," she said. "It is when people arrive in this country that they need the language input. We certainly will need a lot more ESOL teachers.
There are long waiting lists for ESOL classes across the country."
Margaret Lally, deputy chief executive of the Refugee Council, said the organisation had waiting lists for all its language classes. She believes that not enough money is being invested in ESOL.If language classes were to be prioritised for people applying for naturalisation, she said, there would be a danger of a shortage of funding to support classes for newly arrived asylum-seekers.
Helen Sunderland, head of the ESOL division at South Bank university's LLUPlus, a teacher education and professional development centre, thinks there is a shortage of ESOL teachers in London and in some regions, including East Anglia, where there are many migrant farm workers.
"My impression is that there is a capacity problem," she said. "I think it probably will get worse but nobody really knows."
Another problem, she believes, is that on top of the shortage of ESOL teachers there is also a shortage of classrooms in which the subject can be taught and not enough creche places for migrant children.
LLUPlus and the National Institute for Adult and Continuing Education have been commissioned to prepare new curricula materials for the citizenship ESOL programme. But it is telling that in a separate but related scheme, the centre has been commissioned to train some 300 basic skills teacher-trainers in skills for life (literacy, numeracy, ESOL and family learning) by March.
These new staff will be needed to implement the Learning and Skills Council's national Skills for Life initiative.
It seems likely that the Government's commitment to raising the proficiency of English among migrants will mean the UK will need even more ESOL teacher-trainers in future.