In a setback for the long-struggling republican movement, once famously championed by Malcolm Turnbull, more than half of all Australians believe the switch to a republic is unnecessary with 51 per cent opposing such a move and only 42 per cent backing it.

That's down from a high of 58 per cent in 1999 and represents the lowest pro-republic sentiment in 35 years.

The 42 per cent, or roughly four in 10 voters, represents the lowest enthusiasm for a shift to a republic recorded by the Fairfax-Nielsen series since before Kate or William were even born.

Those in favour of keeping the British monarch as head of state account for more than half of all voters at 51 per cent - the highest pro-monarchy sentiment in that period.

Support for a republic reached 57 per cent in the Fairfax-Nielsen series in 1999 - even after the referendum returned a no vote, and has been in incremental decline ever since.

The popular royal couple arrive in Australia on Wednesday and will hold a series of public events as well as meetings with Prime Minister Tony Abbott and Governor-General Sir Peter Cosgrove.

The glamour couple's keenly awaited tour coincides with a royal renaissance measurable in the return to archaic British titles in Australia and the lowest level of pro-republic sentiment in three decades.

A survey of public attitudes suggests our constitutional ties with Buckingham Palace have, if anything, grown stronger with the passing of years.

A decade-and-a-half after the republican movement fell short of its goal when a referendum on becoming a republic returned a no vote, less than half of all voters think it should be pursued at all.

Most notable is the collapse in support for a republic among younger Australians - usually the most change-oriented demographic.

Just 28 per cent of respondents aged between 18 and 24 years backed the idea of an Australian head of state, whereas 60 per cent said no to the idea.