well as someone who has studied concertina accompaniment in depth, I will add some further comments.
Alf never accompanied his own singing as I do, he rarely used single line harmonies, which is something that is easier to do when accompanying others, [this is not meant as a criticism , but just a statement of fact] although i do it to accompany my own singing on occasions, here is an example
http://www.youtube.com/watch?v=iEKVeI_VD3E. n
Alf was not steeped in traditional music, he was a trombonist who played as a session man, but he must be given credit for bringing the concertina to our attention., and inspiring many of us.
I feel that many concertina players would benefit from listening to Swarbricks fiddle accompaniments, whose linear accompaniments are in my opinion outstanding