"are being tutored by some of the finest traditional singers around"
The problem I have here is the term "tutored" - it implies an exclusivity and a teacher-pupil relationship.
In the early 1960s, a group of singers on the folk scene approached one of the greatest figures on the folk scene at the time, Ewan MacColl, and asked him if he would hold "classes".
He refused, but agreed to assist in the setting up of a 'self-help' group based on the idea of a number of singers, with a smattering of non or bog-standard singers, meeting regularly to work on each others singing by listening to individual performances, analysing and discussing the the strengths and weaknesses of the performances and making suggestions as to how it might be improved.
The group became known as The Critics Group, and over the nearly ten years of its existence, produced a body of work which is, to my knowledge, unique in the Folk song scene, though it did give rise to a number of similar groups scattered over England and Scotland - before I joined The Critics, I started one in Manchester.
Ewan and Peggy threw their home open to around a dozen (sometimes more) singers each week and gave them access to their extensive library, archive of field recordings and albums and if necessary, they both were on hand for advice - Peggy gave talks and work-sessions on instrumentation.
Ewan's role during the Group meetings, was to chair the discussions and to help agree on the particular aspects of the singing to be worked on during the course of the evening.
The fact that the work was based entirely on everybody present listening carefully to, analysing and articulating what each singer was doing meant that not just the performer, but everybody in the room was learning and benefitting from the work being done.
The two years I spent in the Critics was, without a doubt, totally life-changing for me - while I was still singing it helped by listen to my own efforts and improve on them, and later, when I slackened off as a singer and shifted to collecting and research, it enabled Pat and I (Pat was a member for several years longer than I was) to organise a method of work to get the very best out of both our continuing self-education on the subject and from the older generation of singers we were taking songs and information from.
The exercises MacColl devised - relaxation, voice production, singing exercises, application of techniques to handle all the different types of song in the repertoire, coupled with the techniques he brought from his theatre days to identify with the songs and make them part of you, really do remain with you for life, as I have fairly recently found out with my own return to singing after a long gap,   
Sandra Kerr was part of that group and I have no doubt that she uses what she took away from The Critics in her work.
She set up a similar group in London for people around The Singers Club at the beginning of the 1970s which she stayed with long enough for it to establish itself; it eventually continued as The London Singers Workshop, independent of any individual leadership - lasted for fifteen years.
The Critics had a minimum of a dozen people and was lucky enough to have an extremely charismatic and knowledgeable figure as a guide.
I have found on numerous occasions that the method of work is equally applicable to a small handful of people who are no more than enthusiastic and not necessarily highly skilled as singers, but who are prepared to devote some time to listen to and advise those wanting help to develop.
On a couple of occasions I have seen a scratch group put together on the spot to work on an individual's singing during week-end singing events.
Individual teaching is a minefield full of dangers of picking up bad habits, idiosyncrasies and personal tastes from others and trying to sound like them rather than yourself.
Group work helps neatly sidestep that without inflating egos.
The basic necessity is to get enough people prepared to devote time to others, to give and accept criticism without throwing a hissy-fit and, most of all, to arrive at a basic agreement on what you understand the songs you are working on are, ("I don't know what folk song is" doesn't hack it) though I have no doubt that many of these techniques are equally applicable to other forms (the whole method of work was a development of that done in Ewan and Joan Littlewood's Theatre Workshop.
Sorry to have banged on for so long - thought I'd put it all together rather than spreading it out over several postings.
Jim Carroll