Just to make sure that the policy of the Singers Club is quoted correctly.
"We were also intent on proving that we had an indigenous folk-music that was as muscular, as varied and as beautiful as music anywhere in the world. We felt it was necessary to explore our music first to distance ourselves from skiffle with its legion of quasi-Americans. The folk club should be place where our native music should have pride of place and where the folk music of other nations would be treated with dignity and respect. So the resident singers of Ballads and Blues decided on a policy that from now on residents, guest singers and those who sang from the floor should limit themselves to songs which were in a language the singer spoke or understood".
Journeyman. Page 288
That would let Ewan sing in Scottish or English as his whimsy took him. It allowed Bert to sing English or Australian songs. I am sure they extended similar privileges to others.