John Lennon and Yoko Ono's first gig in 1969 celebrated

Lennon sat with his back to the audience for much of the couple's 26-minute Cambridge set

The first public gig by John Lennon and Yoko Ono is being celebrated 50 years after it took place.

Ono was booked as part of a jazz performance at Cambridge University's Lady Mitchell Hall on 2 March 1969 and Lennon came along as "her band".

A plaque which reads "Yoko Ono John Lennon Cambridge 1969" has been unveiled in the hall to mark the event.

It comes ahead of a six-month exhibition of Ono's work showing at a number of venues in the city.

The couple's appearance as part of an experimental jazz concert elicited just a few lines in the local and student press at the time, where it was reported that Lennon sat with his back to the small audience for much of the 26-minute set.

Ono on vocals began with a "fearsome siren note" and ended the performance with "a long series of screams".

"Lennon was squatting at her feet, back to the audience, holding, shaking, swinging electronic guitars right up against a large speaker," the Cambridge News reported at the time.

The plaque was unveiled to mark 50 years since Ono and Lennon's Cambridge gig

Ono and Lennon were photographed backstage at the Cambridge concert

Speaking to the BBC in 1980 about the Cambridge concert, Lennon said: "The audience were very weird, because they were all these sort of intellectual artsy-fartsies from Cambridge."

However, he added: "They were totally solid."

Gabriella Daris, an art historian and curator of the forthcoming Ono exhibition which will be on show from June, said: "There's very little to commemorate this other than a press report, word of mouth and the actual recording."

The commemorative plaque was unveiled on the 50th anniversary of the Ono/Lennon gig as their set from the time - called Cambridge 1969 - was played at full blast in the hall's foyer.

It was given as a gift to Cambridge University by Ms Daris.

"The Cambridge concert was the first time ever that Ono and Lennon performed in public in the world," she said.

The exhibition, called "Yoko Ono: Looking For….", will feature more than 90 early, recent and new works by Ono and will run at various venues across the city until the end of the year.

An Ono Wish Tree - for people to post their hopes and dreams - is central to many of the artist's exhibitions

One installation in the exhibition includes TV sets which will broadcast live images of the sky