Its rating valuation included a land value of $7.5 million and an improvement value of $4.85 million.
The previous owners, who could not be reached for comment yesterday, are understood to have bought another property late last year on the same road for $4 million and were redeveloping it.
Mellons Bay, like other coastal suburbs around Auckland's Eastern Bays, has seen solid growth over recent years, with median values climbing from $836,000 in 2010 to $1.13 million last month.
QV described the area as sought after, with many affluent homes having been developed there in recent years.
Many of the modern homes dotted the hillside and commanded brilliant views of the bay's white sandy beaches.
But CoreLogic research analyst Nick Goodall said the Bleakhouse Rd sale still soared above any other sales in the suburb last year.
The next largest was a five-bedroom seafront home in nearby Burford Place, which sold for $2.8 million in July, while three other high-end properties sold for $2.5 million, $1.9 million and $1.2 million.
Mr Goodall told the Weekend Herald there was "nothing specific" about Mellons Bay that could have produced such a huge buy.
"The Bleakhouse sale is a definite anomaly."
Mr Goodall said there was nothing to suggest Auckland was seeing more extreme-end sales, especially given the city's growth.
"As reflected in the new CVs for Auckland there has been a significant increase in value growth across the city," he said.
"Mellons Bay has been no different - except for this one sale."
Because it had been a non-market sale, it didn't feature on a previously reported list of the year's most expensive residential property purchases, which was topped by a luxury penthouse in the central-city Metropolis building that went for nearly $8 million.
It was bought by Singapore-based hedge fund manager Richard Anthony Magides for $7.85 million - more than 17 times last month's national median house price of $455,750.
The next-priciest home, a three-bedroom, 500sq m roughcast mansion at 18 The Esplanade, Takapuna, fetched $7.6 million.
The highest capital value of any home in the top 10 was the $8.8 million CV attached to a beachfront mansion on an isthmus at 17 O'Neills Ave, Takapuna.
The most expensive sale of 2013 was a seven-bedroom mansion on exclusive Paritai Drive partly financed by former Hanover Finance director Mark Hotchin, bought by businessman Deyi Shi for $39 million.
What the buyer got
• $40,000 worth of furnishings
• Tennis court, pool, putting green
• Parking for five cars.
