Mystery has surrounded the "lower north shore" buyer who paid $27 million for a penthouse in the Opera Residences development since the deal was exchanged last November, but is only now revealed as wealthy businessman and philanthropist Robert Salteri and his wife Kelly.

The four-bedroom spread set a national record for the apartment market, topping the $26 million high set just days earlier by the sale of the adjoining penthouse in the same development at Circular Quay.

When it is completed in three years' time the Salteri's four-bedroom spread, set in the building's prime north-facing position overlooking the Opera House, harbour and Botanic Gardens, is planned as the couple's downsizer option from their waterfront home in Northbridge.

Salteri, a keen yachtie and former chief of Tenix, is the son of the late Carlo Salteri, who founded Transfield in 1956 with the Belgiorno-Nettis family before the company was split and the Salteri family took over the defence contracting operations into Tenix in 1997.

In 2014 the BRW Rich Families List ranked the Salteris as Australia's ninth-richest family.

The sale price left many industry experts gobsmacked at the time not only for the bullish result but because the 280-square-metre apartment also equates to record-setting $96,400 per square metre.

The 104 apartments to be built in the old Coca-Cola Amatil building by China-based developers Macrolink and Landream sold out within two hours last November, totalling $500 million worth of real estate.

CBRE director Murray Wood negotiated the deal, but declined to comment for this story other than to say he could not confirm the identity of the buyer.

The Salteris are no stranger to setting property records. Robert Salteri's former home also on the Northbridge waterfront set a suburb high in 2003 when he sold it for $7.13 million.

When they move to their new city pad the couple will be around the corner from the $9.85 million apartment of his brother Paul Salteri, which he purchased with his wife Sandra in 2011.

Paul and Sandra Salteri sold their Castlecrag trophy home, Penhallow, two years ago for $12.8 million.

Fashion retailer picks up Southern Highland homestead

The house Boscobel in Sutton Forest. Photo: Supplied

Meanwhile, Brisbane-based fashion retailer Michael Josephson and his wife Melissa have bought the historic Boscobel homestead in the Southern Highlands for $4.3 million amid talk the couple plan to move there eventually.

The sale ends a two-year sales campaign for the 1870s-built mansion, which has been the home of recruitment industry boss Steven Hallis since 2007. It was most recently listed with Bill Carpenter, of WC Carpenter, who sold it.

Josephson is the co-founder with his brother Greg of the successful lifestyle fashion chain Universal Store, which has bucked the poor market performance of many fashion labels of the past year to report an 18 per cent rise in store sales in 2016.

The 48.5-hectare property in Sutton Forest was the long-time thoroughbred breeding stud of Richard Turnley, the former Thoroughbred Breeders of Australian president, who managed the stud before he bought it in 1979 for $180,000.

Gas man selling Warrawee trophy

This nine-bedroom, 11-bathroom mansion in Warrawee is set to be sold for more than $15 million. Photo: Supplied

One of the Northern Territory's richest men, oil and gas entrepreneur Jerry Ren is selling his trophy home on the upper north shore amid $15 million expectations.

The vast Warrawee estate of 6400 square metres is being marketed as Pantagruel, but was known as Bremon when it last sold for $11.5 million in late 2010, setting a then record for the upper north shore. Locals have long referred to it as the Chilton Hilton thanks to its nine bedrooms and 11 bathrooms.

Designed by architect Espie Dods, it was built in the 1980s for oil magnate Pat Burke, but sold incomplete in 1999 for $3 million to entrepreneur Simon and Brenda Tripp, who completed it. Stephen Sales, of Luschwitz, has the listing.