I admit to having been one of the doubters. When the 2015 Glyndebourne Festival programme was announced, my eyebrows drifted heavenward at the inclusion of Handel’s Saul. Why stage an oratorio when there are around forty of his operas to choose from? However, I reckoned without the inspired Australian director Barrie Kosky, who turns Handel’s 1739 Old Testament oratorio into a gripping psychodrama about King Saul’s descent into madness following the triumph of giant-slaying David. A mere two months after the Festival closed, Saul is triumphantly revived for Glyndebourne’s Tour.

Kosky and designer Katrin Lea Tag create striking stage pictures. To have an audience gasp at the rise of the curtain is quite something. For it to happen twice in the same evening is remarkable. In Act I, just as we discern the bloodied David collapsed in exhaustion beside Goliath’s severed head, the curtain goes up on a cornucopia which is a feast for the eyes: a bewigged chorus in punk-Georgian costumes atop huge banqueting tables groaning with flowers, ripe fruit, stuffed peacocks and swans. A still life of Georgian excess. After the interval, a sea of flickering candles floods the stage to create another breathtaking moment, although for the Tour there is no surprise appearance of Handel as organist rising through the stage floor – conductor Laurence Cummings performing the solo organ parts in the pit, albeit involving a dash from the podium.

An essential part of Kosky’s production is the thick covering of soil through which characters and chorus wade, dance, roll or – in the aftermath of battle – in which they bury the decapitated bodies of Saul and his son Jonathan. It has its problems, not least acoustically. Singers struggled to project, particularly from the back of the stage. In the Foyer Circle, even Anna Devin’s normally pristine soprano didn’t sound crystal clear, muddied by the voice-sapping rubber crumb.

However, Kosky’s production, revived here by Donna Stirrup, is carried out with panache and great stagecraft. Henry Waddington’s long-locked Saul is clearly unnerved at the adulation that greets David’s victory over Goliath and fears his throne is under threat. His jealousy and Lear-like descent into insanity is portrayed brilliantly, particularly striking during the accompagnato “Wretch that I am” and the following scene where Saul suckles from withered breasts of Colin Judson’s unnerving Witch of Endor. It was a performance of heart-stopping intensity.

Benjamin Hulett not only sang mellifluously – a very fine “Birth and fortune I despise” – but also encapsulated Jonathan’s confusion, torn between loyalty to his father and an almost homoerotic attraction to the outsider, David. Christopher Ainslie’s soft-edged countertenor, especially honeyed at the top, gave an otherworldly quality to David, subtly acted. Stuart Jackson’s robust tenor suited the exuberant jester-like figure providing commentary on events, cackling and whooping wildly.

Lear had three daughters; Saul had two. Sarah Tynan exhibited marvellous control of line in “Author of Peace” as Merab, who initially scorned David’s humble origins, pities his plight. Anna Devin moved as a girlish Michal, intrigued and in love with David from the start. Her phrasing and expression was wonderful in “See, with what a scornful air”, as Michal observes her sister’s rejection of David as would-be husband.

This being an oratorio, Handel keeps the chorus busy. Kosky and Otto Pichler keep them busier, requiring spiky semaphore choreography on top of incisive vocal contributions. Cummings led an invigorating, alert account, the Glyndebourne Tour Orchestra sounding a practised Baroque ensemble.

For sheer spectacle, Kosky’s production impresses. Allied to performances of such dramatic truth, Saul is unmissable. Doubts firmly dispelled.