Yesterday morning architectural conservator Guy Williams donned safety gear and climbed a ladder on the castle roof to hoist the flag, which was soon soaring in the autumn breeze.
Castle executive director Norcombe Barker said work to make the flagpole stronger was done after repairs to the roof and the exterior of the building last year. He estimated the entire project cost more than $250,000. It was "fantastic" to see the flag flying again, Mr Barker said.
The extensive restoration work on the castle was ongoing, and was paid for by the "wonderful" tourists going through.
"Places like this do cost a lot to restore," Mr Barker said.
A handrail had been installed on the staircase leading to the castle roof, to make the climb safer for visitors.
