Between them, playwright Ben Power, actors Kathryn Hunter and Richard McCabe and director Helena Kaut-Howson with her creative team have indeed wrought a tender and beautiful thing, a meditation on love, its longevity and endurance in old age and in the face of illness and death.

When young couples vow "till death do us part", it’s unlikely (and probably should be) that they think ahead to what the words will really, eventually mean. In Powers' wonderfully crafted reworking of Shakespeare's Romeo and Juliet, with additions from his sonnets and other sources, time shifts to show two lovers, one couple, at different ages and stages of their relationship. Because it starts with McCabe's endearingly bulky elderly Romeo alone with his grief and his memories, we know the end before the beginning, which makes the journey more heartbreaking, but never mawkish.

In Neil Murray's spare, fluid design the couple's bed is both the marriage bed they’ve shared and then Juliet’s sickbed and eventual deathbed. And the first glimpse of Juliet is of her tiny body wracked by wasting disease, as Romeo tenderly lifts her from the bed.

Hunter’s physicality is extraordinary. In her illness she looks as if a breath would blow her away; yet for her next entrance, in a long red swirling dancing frock, flashing back to the ecstasy of early love with those familiar words “It is the East and Juliet is the sun”, she looks delicate and sturdy at the same time as Romeo whirls her into the dance this couple loves to share.

Actually the words are spoken as a shared joke – perhaps remembering the thrill of their first meeting. Often Powers, interpreted by his lovers, catches and reinforces that delicious special feeling of shared jokes that reinforce intimacy over the years. For this is a love that has not just survived, but grown with the years, until they face the terrible prospect of Juliet wasting away in body and mind. She wants to choose to die before she loses dignity, memory and physical facilities. He must agree to help her.

It's an extraordinary twist on the choices Juliet faces in the original story. And indeed the issues surrounding assisted dying are urgently/sadly topical. But this is so much more than an issue play and Powers does so much more than cut and paste and re-allocate speeches.

Hunter and McCabe wonderfully convey time-shifts by their changing physicality (touchingly, dancing becomes Romeo supporting the wasting Juliet) and the outside world does not impinge on this couple lost in embrace, but there is another dimension to the design. A huge scrim sweeps down to project video-designer Jaques Collin's vast seascapes. His crashing waves, at one point pounding on family photos from childhood on - and also of the couple’s long-dead child - add another storytelling dimension.

Add one more dimension, John Woolf’s plangent music played live by Jeff Moore (violin), Elaine Ackers (cello) and Michael Keelan (keyboard), and you have a miraculously tender and beautiful thing. Extraordinary.

- Judi Herman