Nirvana were renamed The Simon Ritchie Bluegrass Ensemble when they recorded 'In Utero'.

The 'In Bloom' grunge band were so famous after the success of their second album 'Nevermind' they had to be booked into a studio under a secret name to make its follow up.

Brent Sigmeth, who worked at Pachyderm Studios - where the album was recorded - knew something was up the minute a bluegrass outfit were booked in.

He said: ''Immediately we were suspicious. Eventually we figured out it had to be Nirvana. I still had to go to the airport and hold up a sign which said 'The Simon Ritchie Bluegrass Ensemble'. Then I clocked Kurt [Cobain] and Krist [Novoselic] walking off the plane and kinda just waved them down and told them I was their ride.''

The band had rehearsed meticulously for the sessions and Brent says they were very focused during recording of the album at studio, located the tiny town of Cannon Falls, Minnesota.

He added to NME magazine: ''Everyone seemed really prepared. Like they knew what they were going to do. Kurt did most of his vocals in two or three takes. I think it was a happy time for them. For the first week it seemed really down to business and everyone was having fun eating good food and making music. The first thing they played in the studio was 'Scentless Apprentice'.''