barker trained at the central school of speech and drama from 1960 to 1963, in her final year winning the carlton hobbs bursary, which gave her a six-month contract with the bbc's radio drama company. in 1964 she joined the english stage company at the royal court theatre, sloane square, for three plays: "inadmissible evidence" (understudy), "julius caesar" (crowd and understudy), and "cuckoo in the nest", in which she played rawlins. during four seasons with the national theatre company at the old vic theatre between 1964 and 1968 she appeared: "hobson's choice" (as ada figgins), "mother courage and her children" (yvette), "a flea in her ear" (eugenie), "the storm" (glasha), "the dance of death" (jenny), "othello" (crowd), "juno and the paycock" (neighbour), "the crucible" (mercy lewis), "rosencrantz and guildenstern are dead" (courtier and attendant), "volpone" (androgyno). she played miss prue in william congreve's play "love for love" at the old vic theatre with laurence olivier, directed by peter wood.