Professor Peter McDonald is Australia’s leading flip-flopper on immigration (for example, see here, here and here).
In 1999, Peter McDonald co-authored a parliamentary research paper, which concluded that it is “demographic nonsense to believe that immigration can help to keep our population young”, claimed that “levels of annual net migration above 80,000 become increasingly ineffective and inefficient in the retardation of ageing”, while also recommending “a population of 24-25 million within 50 years”.

“Those who wish to argue for a higher level of immigration must base their argument on the benefits of a larger population, not upon the illusory ‘younging power’ of high immigration”, McDonald wrote in 1999