Observations: Curtains raised on sacred spaces and famous faces

The few minutes immediately before an actor or actress takes to the stage in the theatre is sacred; it's a time for total privacy and preparation. Which is exactly what makes the photographer Simon Annand's images, on display in a new exhibition at the Victoria & Albert museum from 25 January, so special. They are an insight into a hidden world.

For the past 25 years, he's been snapping away backstage in the dressing rooms of everyone from Sir Ian McKellen to Jeremy Irons, Tilda Swinton to Rachel Weisz. There's Gillian Anderson, hair in rollers, before What the Night Is For at the Comedy Theatre in 2002; a smiling Rebecca Hall pre The Winter's Tale, which played at the Old Vic last summer; and Jaime Winstone, wearing a top hat and grinning cheekily before stepping on stage at the Hampstead Theatre in The Fastest Clock in the Universe, also last year.

The exhibition title, The Half, is taken from Annand's 2008 book, and refers to those 30 minutes before curtain up. Since the book was published, the exhibition has been on tour around the UK, and it finally arrives back in London this month. Nearly half of the exhibition will consist of new images in colour (the book is mostly black-and-white), including backstage shots taken at some of London's biggest musicals, such as Priscilla Queen of the Desert, Wicked and Hairspray.

"Musicals have more fantasy and a different energy to plays, so the atmosphere in the new photos corresponds and acts as a contrast and compliment to that," explains Annand. "Jason Donovan was fantastic. There's such a myth that exists around the dressing room but all I can say is that the actors are focused people who have their own way of finding concentration. I don't have a wish-list; the people I choose to photograph are people I like. If they want to chat, I'll chat, but I'm not trying to impose anything on them. It's not my studio; it's their dressing room and their world."

The Half, 25 January to 11 April, The V&A, London SW7 (020 7942 2000; Vam.ac.uk)