Thoroughbred auction house William Inglis has confirmed plans are underway to relocate from its historic Newmarket complex at Randwick to Warwick Farm.

Six years ago, Inglis bought 26 acres adjacent to the Warwick Farm racecourse with a view to building a state-of-the-art facility.

Managing director Mark Webster said the recent rezoning of Newmarket meant construction at Warwick Farm could now begin with the complex expected to be finished by the spring of 2018 and the first yearling sale to be held early the following year.

It will include accommodation for 1000 horses, parking for 2000 cars as well as hospitality outlets and a new hotel.

"Visitors will have access to 2000 car parking spots, significantly more than the 400 currently available at Newmarket," Webster said.

"We are also working towards incorporating a hotel on our site to accommodate guests, with a range of hospitality facilities including a bar, micro-brewery, day spa, cafe and restaurants. This will supplement the recently established Holiday Inn Hotel opposite the racecourse on the Hume Highway."

Webster said the WestConnex project, which will provide upgrades to the ring road network around Sydney, would improve travel time from the city and the airport.

"At the moment travel time is around 40 minutes from the city which is the same as our Oatlands property in Melbourne and Karaka in New Zealand is also about 40 minutes from Auckland," he said.

The heritage-listed buildings at Newmarket and the famous fig trees will be preserved when the site is redeveloped as a housing and shopping precinct.