It was vintage Paul Keating on Tuesday. Only on Monday, Sydney Parklands and Botanic Gardens chief executive Kim Ellis had elected to turn the other cheek in response to the former prime minister's eviscerating assault on the new $130 million master plan for the gardens and Domain, which Keating fears will commercialise a ''sacred place'' with a litter of buildings, a ferry wharf, a train station and a permanent sound garden. Now Keating smacked Ellis on the other cheek and derided his career credentials - not in botany but in western Sydney airports, the Hordern Pavilion and Fox Studios.

Then Keating pummelled the Sydney architects who defeated an international field to win the master plan contract, Cox Richardson. ''This is archi-park,'' Keating told ABC Radio 702. ''What you do not need is a Sydney architect anywhere near this. This is landscape architecture. These firms are not qualified to provide advice about landscape architecture.''

Next he accused the Royal Botanic Gardens and Domain Trust and the Art Gallery of NSW of coming to an ''untoward arrangement'' to allow the gallery's plan to extend to the north, leaping the expressway and encroaching on the gardens. Rather, Mr Keating argued, the gallery should extend to the south and build over the Domain car park, where the master plan has instead placed an $80 million hotel.

Mr Keating claimed he challenged gallery director Michael Brand, who had responded that visitors would want the views offered by a northern extension.

''You're just another property tart like all the others,'' Mr Keating said. ''Aren't you supposed to be selling art, Mr Brand?''

It is Dr Brand, in fact, but he was overseas and unable to defend his own honour on Tuesday.

So was architect Philip Cox, who is among industry leaders travelling with Prime Minister Tony Abbott on his trade mission to Japan, but Mr Cox's firm encouraged ''everyone to view the master plan, understand the proposals and get involved'' in the public consultation, which runs until May 4.

Mr Ellis turned his cheek, yet again. ''It's just not the way I do business,'' he said of the attack on his credentials. ''I would love the opportunity to brief Mr Keating and correct some of the errors he's made, but I'm not interested in getting into a fight with him. I'm still keen to get his feedback.''

Mr Keating was wrong, he said, to quote from an early draft of the master plan that the proposed reception centre for the gardens, to be built at the foot of the Opera House, would have 200 seats and another 100 outdoors. The trust had engaged Mr Keating last year to seek his preliminary views on the plan, and those seat numbers were deleted from the released master plan ''largely because he and other people said it was too much''.

The trust said the centre would ''merge into the landscape - and sit within the slope - with a rooftop landscaped area, extensive use of glass and stunning Opera House and Sydney Harbour views''. Joern Utzon's original Opera House plans had allowed for a similar structure.

Mr Keating wants to defend ''the essence of naturalism''. Mr Ellis believes the existing asphalt viewing platform at Mrs Macquaries Point and the nearby shipping container-like structure that sells burgers and coffees are far from pristine, and will be improved by a less obtrusive grass platform, beneath which will be secreted toilets requested by the public.