This thesis combines traditional and practice-based methods to research the representation of age and ageing in contemporary British theatre. My voice interjects intermittently in the thesis in acknowledgement of my culturally and historically situated position as a middle-aged female theatre-maker. In search of performances that might counter the normative narratives of decline and disappearance that pertain to age (Margaret Gullette, 2004: 13), I look, in Part I at professional performances, considering mainstream dramas and contemporary autobiographical performances. I conclude that the latter, presented in postdramatic rather than dramatic mode, have the potential to unsettle the identity position of ‘old’, especially that of ‘old woman’. In addition, drawing on Judith Butler’s notion of the ‘effect’ of gender as produced by cultural apparatus (2006: 199), I propose the notion of age-effects, noting production of these in performances I see and make. Part II discusses three practice-as-research performances: Life Acts (2013), A Blueprint for Ageing (2014) and The Mirror Stage (2015), produced with Passages Theatre Company, for performers over fifty, which supported this research. I include audience and cast responses to analyse the potential of these performances to ‘trouble’ the normative figure of the old person and disrupt the meanings that attach to the old body, both in performance and everyday life. Across both parts I enlist the theories of several writers to develop my analysis. In addition to Butler’s and Gullette’s insights I employ Ann Basting’s perception of the aged ‘body in temporal depth’ (1998: 22); Kathleen Woodward’s notion of ‘the mirror stage of old age’ (1991: 69); Anca Cristofovici’s analysis of the aged body in photography as ‘significant form’ and ‘accomplished shape’ (1999: 275); and Beverley Skegg’s ideas of cultural inscription of identity onto the body (2004: 1), in order to develop new insights into how performance can unsettle the identity position of ‘old’.