We knew, after the initial flurry of controversy when this show was announced, that there was going to be no Judy, no Dusty, no Barbra, no Liza. Gay Icons, the exhibition, would recast the notion of what a gay icon was, and those who expected divas with fabulous voices, frocks, pill addictions and capacities to suffer were in for disappointment. A ten-strong panel of the gay great and good, chaired by Sandi Toksvig, would choose their “icons”. Their choices, on paper, sounded dull — personal icons rather than collective ones; cliquey and select.

Yet the exhibition, with a wonderful, accompanying hardback book, is colourful, intimate and moving. It ranges widely and touches on many lives, famed and unknown. The show, which opens in the week of the 40th anniversary of the Stonewall riots and the week of Gay Pride, is spread through three rooms.

Waheed Alli chooses the Village People; Lily Savage, the porn star Jeff Stryker; David Hockney, Diana, Princess of Wales, and Will Young. It’s a tellingly mixed selection — the Village People brought gay archetypes centre stage, some of Hockney’s key works hum with homosexuality — but Lord Alli’s testimonials are terribly formal. His choices also reveal a central weakness of the show: only a handful of photographs are great pictures, arresting and stunning in their own right.

The exhibition’s power doesn’t come from the images, but from the juxtaposition of so many lives and influences. Alan Hollinghurst includes the poet Thom Gunn (cockily handsome, in leather jacket in the 1950s), Warhol muse Joe Dallesandro and “radical homosexualiser” Ronald Firbank. Sir Elton John’s selection is lively, from the piano player Winifred Atwell to Gianni Versace and John Lennon. Sir Elton’s choice also includes the show’s strangest selection: Graham Taylor, the former manager of Watford FC.

A playful momentum is maintained by Sir Ian McKellen (whose heroes include Edward Carpenter and Walt Whitman, both looking beardy and lusty) and by Ben Summerskill, the Stonewall lobby group chief, who writes wittily on Martina Navratilova and Joe Orton. Sir Chris Smith chooses Alan Turing, the code-breaker who committed suicide. In the last room Sarah Waters and Sandi Toksvig surf from k.d. lang to Denton Welch, to Peter Tatchell, in a mock-police mugshot with the badge “Queer Terrorist”.

This show is far from encyclopaedic, but there is much to make you smile and think deeply. Judy may be absent but you won’t miss her.

Gay Icons, National Portrait Gallery, WC2, July 2 to Oct 18

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