WCXX

The creators of the show have greatly embellished this simple story. Here the princess, Althea, takes a deliberate decision to become so light hearted she floats following the death of her mother and brother. It is her way of blocking out pain and responsibility. And the show adds a political dimension, undreamt of by MacDonald, in which the Princess's country Lagobel is in conflict with its neighbour Sealand, the home of her Prince. There's lots of earnest stuff about the wickedness of war, the evils of patriarchy and the need to protect the water supply. You feel you are being preached at.

The songs – and there are so many of them that the NT doesn't bother to list them in the programme – feature a lot of wailing vocals and only very occasionally run to a decent tune or a witty lyric. The orchestrations for woodwind, strings and piano seem fussy and I can't say that any of the numbers lodged in my memory on first hearing.

Rae Smith's designs create a gaudy fairy-tale world with more than a touch of Walt Disney about it. There are birds and dinosaurs flying around on bendy poles and even a cute puppet mouse. And the enchanted lake is pure kitsch with its gaudy water lilies and amphibian creatures. Unlike War Horse the designs here leave nothing to the audience's imagination.

There are some fine aerial sequences, not least when the Princess swoops into the arms of her lover, and I rather liked the low-tech approach in which we see black-garbed acrobats cleverly holding the princess aloft with complex lifts and contortions. There are also some notably dark moments, especially when grotesque suitors cruelly seek to cure the princess's weightlessness.

Rosalie Craig, who resembles the young Tori Amos, proves a beguiling princess and manages to sing superbly even when being manhandled. Nick Hendrix is a touch bland as her handsome lover but Clive Rowe makes the most of a big operatic number of guilt and grief as her father. But this show about a floating princess feels ponderous rather than as light as air and never quite achieves dramatic lift-off.

Booking to Jan 9; 020 7452 3000; nationaltheatre.org.uk