It was when former prime minister Paul Keating was just 15, while he watched in disappointment as the old Sydney finger wharves were replaced by yet more concrete, that the first little spark of an idea for Barangaroo Reserve was born.

More than half a century later, standing in the same area, he has seen the idea come to life.

Keating joined the NSW premier, Mike Baird, on Saturday to officially open Barangaroo Reserve to the public, addressing a crowd of hundreds by the foreshore in the Sydney sunshine.

“This was always the dead part, the grungy part,” Keating said of the headland. “It was lost to us and it’s now coming alive.”

With the Harbour Bridge as backdrop, Keating said he was “overwhelmed” by the reserve – which in the space of several years has been transformed from a concrete shipping container yard into a naturalistic parkland.

But there were times Keating doubted this dream for the area would ever be realised. In 2011, after years of campaigning for the western side of Sydney’s central business district to be returned to the public, he resigned as chairman of a key panel set up to oversee the design of the Barangaroo development.

He accused then-planning minister Brad Hazzard of trying to muzzle him.

Even Baird acknowledged the work Keating had put in.

“Obviously, we don’t agree on everything politically but I have absolute admiration for a man that had a vision here and to see it realised,” Baird said.

“Criticism has come ... There was a push and desire to take away this headland and this park, but Paul Keating said it must stand, it must be in this shape, it is incredibly important.

“He pushed back all that criticism, all that resistance, and today there is not one word of criticism. There is jubilation for delivering something so fantastic for this city.”

Paul Keating in full flight in a special Barangaroo #bairdseyeview, offering some leadership tips for politicians. https://t.co/TMcQu5jcCi — Mike Baird (@mikebairdMP) August 22, 2015

Baird and Keating acknowledged the part both sides of NSW government had played over the years under various leaders to bring Barangaroo Reserve to fruition.

Public transport is expected to further open up the area, particularly a new stand-alone railway network, The Metro.

“The second harbour rail crossing, The Metro, will come through here,” Baird said, adding construction is under way and the entire network will be complete within 10 years.

Barangaroo Reserve is based on the pre-European settlement shoreline, using 75,000 plants native to Sydney. About 10,000 sandstone blocks were mined from the headland to create a foreshore.

“This will be more representative of any headland as it was before European settlement than any other,” Keating said.

He also said it was an opportunity to pay respect to, and acknowledge the history and long contribution of, the Indigenous Australians to the land.