“WE know what she did; I wanted to know why she did it,” said Amanda Whittington, explaining why she has dug up the corpse of murderess Ruth Ellis’s story, to retell it from the distaff side.

It would be too simplistic to say this portrait of the last woman to be hanged in Britain is the Ruth, the whole Ruth and nothing but the Ruth, although the unfaithful lover she shot outside a Hampstead pub in 1953 – motor-racing playboy David Blakeley – is never seen on stage.

And yet he is always there, always on Ruth’s mind, his presence sometimes signified by the sound of a gun; other times by male figures she mistakes for David; and at all times by an obsessive love that is at the heart of Whittington’s findings from her extensive research of documents and biographies.

The first half sets up Ruth’s back story, narrated by the investigating Inspector Jack Gale (Mark Meadows) with a grim air of detachment, a distance from which that half suffers too. You may remember Dance With A Stranger, the 1984 film about Ellis with Miranda Richardson and Rupert Everett, and that is the prevailing feeling at half time. You are still dancing with strangers, still waiting to be inside Ruth’s mind and rather wishing that upper-middle class David had been there to provide a physical sense of why she was so obsessed.

Instead, we have a snapshot of East Ender Ruth’s life as a Soho club hostess, provided by not only the violently abused yet resilient Ruth (Faye Castelow), but also her seen-it-all manageress Sylvia Shaw (Hilary Tones), precocious starlet Vickie Martin (Maya Wasowicz) and kindly young cleaner Doris Judd (Katie West).

Stick with it because The Thrill Of Love improves hugely after the break, doing exactly what the half-time chat had sought. After the satin, here is the steel, with a terrific lead performance from Castelow, particularly in the key scene where, body broken and bloodied, Ruth is nevertheless desperate for David to be let in.

The closing scene is a revelation too: her final, sobering statement, too late to save her, before hangman Pierrepoint went to work.

Whittington ultimately succeeds in her aim of making you think again about the psychological circumstances behind Ruth Ellis’s actions; the role of women at the time; and the attitudes of a world still dominated by men in suits.

The Thrill Of Love, New Vic Theatre, on tour at Stephen Joseph Theatre, Scarborough, until March 30. Box office: 01723 370541 or sjt.uk.com