An online auction has struck a sour note with the Catholic and Anglican dioceses.

A baby grand piano advertised on Trade Me sold for $6000 this week. The seller listed it as "Grand Piano from Christchurch Cathedral".

The listing said the seller, called Bridgewater, bought the mahogany piano at a charity auction in 1995.

"This piano was originally the only piano in the Christchurch Cathedral up until then," the listing said.

However, Anglican musician Lennox Willett and ChristChurch Cathedral administrator Chris Oldham do not remember it.

"I have no recollection of there being a grand piano in the cathedral prior to the current one, which is still inside," Mr Oldham said.

"There were two upright pianos, a Steinway in the choir vestry which has been retrieved and an old Yamaha in a room in the tower which was sadly destroyed in the quake."

Mr Oldham suggested the seller may have confused ChristChurch Cathedral with the Catholic Cathedral of the Blessed Sacrament.

"It's certainly a little strange ... it may have left the cathedral many years before that [1995] but it certainly hasn't been there in my living memory."

Catholic cathedral music director Don Whelan said the piano pictured on Trade Me "certainly was not" in the cathedral, where he has worked for more than 40 years.

The seller said the Rogers of London piano was being sold "reluctantly". A Trade Me user asked how much it was bought for in 1995, but the seller could not remember.

Trade Me contacted the seller on behalf of the Press yesterday but there was no response.