Jo Ann Kelly:

Traditionally minded singer of country blues material - her own and others - and a true keeper of the flame. Sister of Dave Kelly of The Blues Band.

Sometimes musically involved with the electric blues scene of the early days:
Sat in with the early Yardbirds.
Recorded limited edition EP with Tony McPhee in 1964.
Supplied vocals on John Dummer Blues Band's albums "Cabal" MERCURY SMCL 20136 (1969) and "John Dummers Blues Band" MERCURY SMCL 20167 (1969)
Also vocals (under the name of Memphis Lil) on the album "Tramp" MUSIC MAN SMLS 603 (1969) by a loose outfit of well known U.K. bluesers, sometimes also referred to as Tramp.

But generally working alone with her acoustic guitar handy - a singer/songwriter par excellence. Just like her 'idol', Memphis Minnie.

Paul Jones, also of the Blues Band wrote in the liner notes to "Retrospect 1964-72":
"This is a remarkable woman.
Her entry in Sheldon Harris's Blues Who's Who (and the first remarkable thing is that a white English woman has an entry in it at all) tells us that Jo Ann Kelly's recorded performances have been released on labels like Epic and Columbia, as well as Blue Goose and Red Rag. Also that she has worked extensively in America in addition to Britain and continental Europe. And it quotes Ian A. Anderson (of 'Folk Roots' magazine) as expressing the opinion that Jo Ann is 'unquestionably the queen of British country blues singers'."
Links:
I'm no expert on this gifted lady, so please jump to
Jo Ann Kelly discography by Stefan Wirz. Excellent site!