After a phenomenal decade-long run, the Cursed Child two-parter is being pruned. Will it still work? Our writer swishes her cloak, levitates her luggage – and hops aboard the streamlined Hogwarts Express

‘Silencio!” Two dozen tank-topped and T-shirted figures fall quiet, and look expectantly at movement director Nuno Silva. “If you’ve got a cloak, accio it now …” With that summoning charm cast, broomsticks are stowed, wands holstered, suitcases grabbed.

The Harry Potter and the Cursed Child rehearsal room – a creaky church hall whose Victorian wall clock gives a serendipitously Hogwarts flavour – is a near-permanent bustle of activity. A sound technician quickly re-sets cues on her laptop, a costume designer helps an actor into a suspiciously long pair of gloves. Associate director Nicola Samer is quietly running notes with a couple of the leads while the rest of the company preps for the next scene.