Rather than just having a passport to present when landing, tourists will now also need pre-travel authorization to get on a plane to the UK.

The ETA is a new visa waiver required to travel to the United Kingdom for any trips that last six months or less for business ...

Australians with dual British or Irish citizenship are exempt from the ETA process if they use their British or Irish ...

Australians with dual British or Irish citizenship don't need an ETA if they are travelling using their British passport, Irish passport or other passport that contains a certificate of entitlement.