Mentoring has been regarded as a panacea for overcoming barriers to learning - whether a pupil has behavioural problems or difficulties at home, is on the verge of exclusion or has suffered a bereavement.
Ministers and inspectors have been quick to praise its influence. The Office for Standards in Education has hailed mentoring schemes as a huge success story in the otherwise patchy Excellence in Cities programme. In a recent speech, David Bell, the chief inspector of schools, said mentors were the most successful and popular feature of EiC.
"The creation of the posts was welcomed by the schools and enabled the majority of them to offer better support to disaffected, vulnerable and underachieving pupils," he said.
"Learning mentors make a significant impact on the attendance and behaviour of the pupils they support."
Mr Bell also values the links forged between schools and their local communities through mentoring. Inspectors have claimed that mentors had the greatest effect on exam results as well as behaviour of any of the EiC "strands". And a National Foundation for Educational Research survey of 2,000 teachers and managers in EiC schools found that they were impressed with learning mentors.
Ministers are also keen, though more equivocal. Last year, the schools minister David Miliband announced the appointment of another 1,400 mentors.
"I am very pro learning mentors, but they are not the only club in the bag," he said recently.
On the other hand, recent reviews of the research evidence have cast some doubt on whether mentoring really works.
A study of UK research into mentoring by the Scottish Council for Research in Education (SCRE) reports that proponents tend to make large claims for its success based on flimsy evidence.
"There is a very poor evidence base in the UK," said John Hall, senior researcher at SCRE and author of the report. "Claims are made for the impact of mentoring but there is as yet little evidence to substantiate them."
According to Dr Hall, even the large-scale studies carried out in the United States indicate only a limited influence in specific areas.
US mentoring has had its biggest successes with young people who have difficult or high-risk behaviour, and the best results have been achieved in education and employment. But researchers in the US have also questioned the overall impact of mentoring programmes.
The most thorough research review carried out there - for the National Institute of Justice, Washington - found that community-based mentoring schemes could only be described as "promising". The researchers concluded that there was too little information to justify support from policy-makers.
"The priority is for more research, not more unevaluated programmes," the study said.
"The danger of doing harm is far too great to promote and fund mentoring on a broad scale."
But if doubts are now surfacing about mentoring's efficacy, it is vital not to throw out the mentoring baby with the research bath water, according to Michael Shiner, senior research officer at the Mannheim Centre for Criminology at the London School of Economics.
Dr Shiner is co-author of the most extensive and rigorous evaluation of mentoring ever conducted in Britain, published last month.
"One of the dangers is that people fasten on to something which is billed as a wonderful panacea, then a negative research study comes out and they move on to the next thing," he said.
"It's too simple to ask, 'Does mentoring work?' We need commitment to discover what mentoring can do and the circumstances in which it will succeed."
The results of Dr Shiner's research into 10 Mentoring Plus programmes run by Crime Concern - involving 370 12 to 19-year-olds at risk of social exclusion - makes him guardedly optimistic about the value of mentoring.
Thc research found that the proportion of participants in education, training and work increased from 49 to 63 per cent during the programme.
There was no change among a similar "high risk" group of young people who had been referred to the programme but did not take part. Most of the participants considered the mentors to have been helpful.
Yet there was no evidence that mentoring had any effect on improving family relationships or self-esteem, or on reducing crime and drug and alcohol use, even though the general aims of the programme were to target such problems. Dr Shiner believes that planners must have more realistic goals and should tailor projects more carefully to achieve the desired results.
The LSE study also found that the difficulties of engaging with disaffected young people in the Mentoring Plus scheme were exacerbated by insecure funding, fixed-term employment for project workers and high staff turnover.
The researchers warn that potentially positive work with young people could be undermined by such uncertainties.
A picture is certainly emerging of what works in mentoring and what does not. US research suggests several key features in successful mentoring, including monitoring of programmes, screening and training of prospective mentors, structured activities, parental involvement and long-lasting contact between mentors and mentees.
Not surprisingly, young people who have high-quality relationships with their mentors enjoy the greatest benefit. The young people in the Mentoring Plus scheme defined the most important characteristics as: being able to talk, reciprocity, a relationship based on respect rather than authority, a genuine understanding and interest in young people on the part of the mentor, and having fun.
Similarly,a study undertaken in Scotland by researchers at Aberdeen university revealed that the ability to "have a laugh" with a mentor was crucial to sustaining a relationship. Young people also particularly valued mentors who were willing to discuss their own experiences and who shared similar backgrounds.
Evidence from the US indicates that one of the main obstacles on the path to success in mentoring is a mismatch between the values of the mentor and mentee. Other hurdles include inexpert mentors and a conflict in the role of mentors which leaves them unclear about whether they are acting as authority figures or as advocates for the young people being mentored.
The researchers also point out that the concept itself is ill-defined.
"A lot of mentoring takes place quite naturally and is indistinguishable from friendship," said Dr Shiner.
The eclectic nature of mentors' identities was also re-echoed by Mr Miliband recently. "Reading champions, fathers, brothers, mentors are encouraging boys to put down the TV remote control and read," he said.
Whatever the arguments, the main message seems to be that the Government needs to be more down-to-earth in its expectations.
Dr Shiner said: "State money is being poured into combating disaffection but we continue to see rising crime and illiteracy.
"We need to be realistic about any sort of intervention, particularly if it is based on the involvement of volunteers."
Mentoring disaffected young people: an evaluation of mentoring by Michael Shiner et al.Sharing a laugh? A qualitative study of mentoring interventions with young people by Kate Philip et al. For more details see www.jrf.org.ukMentoring and Young People: a literature review is available from the Scottish Council for Research in Education. Telephone 0131 5572944
AN ONGOING DIALOGUE TO BOOST SELF-AWARENESS
Djanogly city academy in Nottingham has a tightly-focused system of mentoring which involves the local universities.
Post-16 students are mentored by university staff. For instance, those on A-level English courses use a virtual learning environment to build contacts with staff from the English department at Nottingham university.
There are no volunteer mentors at Djanogly - all the lecturer-mentors are remunerated by the university.
Mentoring for 11 to 16 year-olds is provided by two experienced learning mentors who are employed by the school.
"The role of the mentor is to remove the blockages to learning," says Showkat Badat, deputy principal at the city academy.
"The focus is on improving academic performance through setting targets and developing skills such as organisation, revision and time management.
"Targets are reviewed on a weekly and termly basis."
The programme is voluntary and students are interviewed initially to see whether they would benefit from mentoring.
The target group is made up of those pupils who have the potential to gain GCSEs at grade C or to achieve level 4 or 5 in Sats but who may be struggling to do so. The aim is to boost students' confidence and performance by providing extra support and developing their learning skills.
An evaluation last year showed that students were very positive about the programme.
"They felt it increased their self-awareness and the Year 11 students who took part achieved better exam results than the school had projected," says Mr Badat.