The powerful and moving evocation of an entertainment icon, combining classic singing with a fully-realised dramatic story, with a remarkable central performance and solid supporting cast, make this portrait of Judy Garland’s last hurrah a high point, if not THE high point of the festival.

Rather than a typical biography show, author Peter Quilter focusses on a few days in 1968 as Garland essays yet another comeback in a London cabaret engagement, supported by her soon to be fifth husband Mickey Deans and a fictional composite gay accompanist but without the support of pills and liquor. Tragically, she discovers that after years of dependency, she simply cannot make it through a performance without chemical aid and equally tragically, that even those who love her the most will eventually make draining demands on her dwindling emotional resources.

A show like this lives or dies with its central performance and Caroline O’Connor delivers. Singing at least parts of a dozen Garland classics, she captures the sound and style with uncanny accuracy, along with the familiar physical mannerisms. Close your eyes and it is Judy, open them and it’s still Judy.

But this is not merely a drag queen impersonation. O’Connor subtly distinguishes between Judy singing with confidence and authority and Judy singing on the edge of her nerves, while showing that both were spectacular. In the dramatic scenes, she shows how Judy could be charming, bitchy, desperate, violent, pathetic and hilarious, often within seconds and makes it clear that the singer is always walking an emotional tightrope from which she knows she must eventually fall.

O’Connor is not alone onstage, however much her bravura performance dominates it. Michael Cormick makes Deans a solid, loving man willing to take on the mantle of Mr Judy Garland, even if it requires him to be painfully cruel, or to end up supplying the drugs he had begun by bravely withholding. Jonathan Gavin makes a sympathetic and ultimately flawed individual out of a character who is an embodiment of Garland’s gay fan base. End of the Rainbow has already won awards in its native Australia and must have a stage life beyond Edinburgh.