The jailhouse snitch known as "Witness C" who gave false evidence at David Tamihere's double murder trial has failed in his bid to have his sentenced reduced.

Roberto Conchie Harris, was revealed as Witness C earlier this year after he abandoned his appeal against the perjury conviction.

His identity had remained suppressed for 27 years.

Harris, however, continued with his appeal against his sentence claiming it was "manifestly excessive".

He was sentenced in the High Court at Auckland to eight years and seven months' imprisonment by Justice Christian Whata.

In its decision delivered today, the Court of Appeal said it had no doubt that Harris' perjury "falls into the more serious category of offending" and that a nine-year starting point adopted by the judge was well within that available to him.

"The end sentence could not be described as manifestly excessive."

The appeal was heard by Justices Helen Winkelmann, Raynor Asher and Brendan Brown.

Harris was last year found guilty on eight perjury charges relating to having lied at Tamihere's trial in 1990.

Harris, a double murderer, sex offender and fraudster, was convicted in a private prosecution brought by "jailhouse lawyer" Arthur Taylor.

Harris was one of three prison informants who claimed at the 1990 trial that Tamihere had confessed to murdering Swedish tourists Sven Urban Hoglin, 23, and Heidi Paakkonen, 21.

Tamihere, who has always professed his innocence, was convicted and sentenced to life imprisonment, before eventually being granted parole in 2010.

Tamihere has exhausted most legal avenues but is still hoping to file an application for a Royal Prerogative of Mercy with the Governor-General or seek a pardon.