Rare and unseen photographs of Irish rock stars Phil Lynott and Rory Gallagher performing together on stage have been found after almost 30 years.

The discovery was made two weeks ago by photographer Colm Henry when he was trawling through his archives. Colm who is originally from Co. Meath was Ireland's top rock photographer and spent much of the 1980s capturing shots of the biggest names in music. However moving houses several times over the past few decades resulted in him mislaying several valuable shots.

"I still have the negatives but many of my proof sheets are gone. In the case of the picture of Phil Lynott and Rory Gallagher together in 1982, I found it in a file of Phil Lynott images from 1986."

"Thin Lizzy weren't even playing at that concert. Phil Lynott just turned up and decided to get onstage with Rory. It's not like Oxegen now. Things were a lot looser back then and that could happen," Mr Henry told the Irish Independent.

The image was taken in the summer of 1982 during an open air concert at Punchestown Racecourse.

His collection also includes a photograph of a young fresh-faced Sinead O'Connor awaiting a flight in Dublin Airport in 1985.

"Sinead was going over to London to sign her first record deal. I had given her a lift to the airport. That's the way it was in Dublin in the '80s. Sinead told me recently she regards this picture as capturing a seminal moment in her career," said Mr Henry.

The 57-year-old has also captured iconic shots of U2, Leonard Cohen, Shane McGowan and David Bowie. He recalled how security for big acts was not what it is today.

"The great thing about when big acts came to Ireland in the 1980s is that they arrived with no handlers and no entourage, this meant they were very open to suggestion.

"I can remember, rather than being quiet, Leonard Cohen didn't stop talking about his new girlfriend, an Italian fashion designer. He really was in love back then," said Henry who photographed Cohen at Jury's coffee dock in the early 1980s.

"Access to artists stopped because merchandise lawyers took control of the bands. At the same time I wanted to move on. I began to work in theatre, and then later for 'VIP' magazine doing glamour shoots, " he said.

Mr Henry opened up a gallery of his famous rock images in Dun Laoghaire Shopping Centre in Dublin earlier this week.