It is most unusual to get a recording of this outstanding quality

Isles FM DJ Rodney Collins

Mr Collins said Soliloquy, from the musical Carousel, had been recorded live on Sinatra's 73rd birthday at a US club in 1988.

Isles FM, which is based in Stornoway, received the recording from a Sinatra fan who attended the private concert.

"This is quite a scoop for Isles FM and I am just delighted to have been sent this and to be able to play it here in Scotland," said Mr Collins.

"It is unlikely that this will ever be released in the UK, or indeed elsewhere in the world, so that makes this even more special."

The track will be played on the presenter's afternoon Drivetime show on Wednesday.

The song is unlikely to be released

"It is most unusual to get a recording of this outstanding quality," said Mr Collins, who has previously produced Sinatra Hour programmes at London radio stations.

"There is a lot of Sinatra material similar to this about but it is usually quite muffled.

"This is exceptionally good quality and I am sure all the listeners who tune in to hear it will not be disappointed."

Mr Collins said the song had been suggested to Sinatra after he asked his producers to recommend something different for him to sing.

"It's an 11-minute epic that would be difficult for a young man to sing. It really is an extraordinary performance," he said.