With the Duke and Duchess of Cambridge and baby Prince George arriving in Sydney this week, comparisons with the visit by the Prince and Princess of Wales when Prince William was a baby are inevitable.

It was more than 30 years ago - in March 1983 - that republican supporter and builders union shop steward Stan Spurek had a bizarre encounter with Diana, Princess of Wales, that became a story that went around the world.

Mr Spurek had the audacity to present Diana on a visit to the New Parliament House construction site with a small Eureka flag, telling her it was a republican flag.

Now aged 66 and living at Moruya, south of Batemans Bay, Mr Spurek said he thought it was a good idea at the time, as the republican cause was being pushed.

''Princess Diana got in on the other side of the Rolls and slid across and I knew the window was open,'' he said.

''I said, 'I would like to present you with this flag'. She accepted it and said it was pretty. I said it's a republican flag but she had no idea what I was talking about.''

A cartoon appeared shortly after with Diana showing the flag to Charles and him saying, ''Mummy will not be pleased''.

Asked if he thought the republican cause had advanced since then, Mr Spurek said: ''We probably won't be a republic in my lifetime. The way politics is going, we don't know what the bloody hell is going to happen.''

The Duke and Duchess of Cambridge arrive at Sydney airport on Wednesday afternoon. Their itinerary includes visits to the Sydney Opera House, the Blue Mountains to meet families affected by the bushfires, the Easter Show and a trip to Taronga Zoo.

David Flint, national convener of Australians for Constitutional Monarchy, said the visit by the Duke and Duchess was ''the icing on the cake''.

''I think there will be a big turnout, particularly at the Easter Show, with a lot of people there to see them,'' he said. ''I think there is great interest in the baby.''

Women's magazines are planning comprehensive coverage.

New Idea's next edition has two posters, a flag to wave (not the Eureka flag) and prominent features. Editor-in-chief Kim Wilson said there was a strong appetite for royal coverage.

''The royal family, particularly little George and Kate and Wills - there's still a lot of affection for them no matter where you stand on the republican spectrum,'' she said.

''The royals coming to Australia, especially two future kings of England, is an exciting time.''

*The Eureka Flag, which bears the Southern Cross, was first unfurled in 1854 in protest against the colonial authority of Britain.