How are we defining a traditional singer here?
I've collected songs written by a local (Cumbrian) singer, who used to sing his own self-penned to someone else's guitar accompaniments as well as perform 'traditional' ballads.

Also in Cumbria Vaughan Williams, Frank Kidson and Cecil Sharp all collected versions of songs which had been written by 'The Cumberland Bard' Robert Anderson (1770-1833) but passed into 'the tradition' (sorry, but I seem incapable of writing traditional without adding inverted commas!)

Peter Kennedy also collected hunting songs in Cumbria which were written if not by the singers themselves then by people of just the generation before. Many hunting songs which are regarded as 'traditional' have known composers.

Incidentally Kennedy was contracted by the BBC to do this (I've seen a copy of the contract) and given a budget to pay singers with, if necessary. However the money was not used for singers, nor repaid as far as I can see, AND Kennedy subsequently released these recordings comercially under his Folk Tracks/Folk Trax label - but that is a whole other can of (fairly well-known) worms ...