The success of student tutoring schemes is very easy to measure in one way. Five years ago there were just four schemes, helped with BP cash, sending students in to local schools as tutors. Now there are 180.
Last month, BP held its first international conference at Queen Mary and Westfield College to mark the success of the tutoring and to spread good practice. More than half the delegates came from abroad, from 34 countries.
Whereas three years ago the BP initiative was linked to just three such schemes abroad, now there are nearly 20, and the figure is expected to double after the conference.
But in other ways the success of the schemes is more difficult to measure. Do the school children really benefit? Are more going on to higher education as a result of their contact with students? And do students' communication skills really improve as a result?
John Hughes, who was one of the original tutors with Imperial College when it pioneered the idea 20 years ago and who now coordinates the initiative for BP, says that a lot of the evidence for the schemes' success is anecdotal.
Students are vocal in their support. Melvyn Boey and Paulina Change of the London School of Economics, who became tutors through the North London Connection Tutoring Scheme, said: "It was wonderful being able to assist and to expose young people to tertiary education."
Initial fears that the students would be used as cheap labour, and so threaten teachers' status, have not materialised. "We stress to students that they are only there as helpers," says Mr Hughes.
But perhaps some of the most conclusive evidence of success comes from Meenal Gupta of the Tower Hamlets Education Business Partnership. Ms Gupta co-ordinates East London Connection, which links three universities and three colleges of higher education with 48 schools. In all more than 400 students take part.
Recently one school measured the impact of one to one reading work at George Green School in Tower Hamlets. Students sat with just one pupil and helped them with their reading over five weeks. The children's reading ages were tested before and after.
Ms Gupta describes the results as "quite startling". The reading ages of the children showed an improvement of up to two years, with the minimum improvement being six months.
The picture is not entirely rosy. Some of the schemes can be costly, especially when it is necessary to employ a coordinator.
Sinclair Goodlad, who established the first scheme at Imperial and is a world authority on tutoring schemes, said that the Imperial scheme itself may be for the chop - a final decision will not be made until after Easter.
Some of the schemes, especially those outside the United Kingdom, may adopt a mentoring, rather than a tutoring, model.
Marc Freedman, from a student mentoring organisation in the United States called Public/Private Venture says that mentors work outside the classroom and really provide "supplemental parenting" rather than "supplemental schooling".
In the US there are 70,000 such matches across the country, with 40,000 school children on waiting lists searching for a mentor. "These schemes have been very successful, but they can involve tremendous commitment from the mentors," he says. "They should be introduced with care."
Great inequalities in wealth can make it hard to judge the extent of a mentor's responsibility. If a child is about to be evicted with his or her family, and the mentor is wealthy, then a request for a loan may be very natural - but could also break the relationship.