The locomotive – known as an ROD after the Railway Operating Division of the Royal Engineers – is 99 years old, having been built in April 1918.

It was used in France at end of the Great War, as hostilities came to an end, and thousands of soldiers were repatriated.

In post-war years, the locomotive was purchased by coal baron John Brown for use on his Richmond Vale Railway, linking his coal mines in the Kurri Kurri district with coal loaders at Hexham.

It operated under the running number ROD 23.

“After withdrawal from service, the locomotive was displayed at the former mining museum at Freeman’s Waterhole,” museum chairman Peter Meddows said.

“It was then gifted to our museum by Coal and Allied Industries, the successor to John Brown’s companies.”

Mr Meddows paid tribute to the work of museum volunteer Graham Black, who has led the restoration of the locomotive.

“Graham’s detective work has identified which parts have stayed with the locomotive throughout its life, and the few which have come from other locomotives at overhaul time, thus confirming its origins,” he said.

“He has led a small but dedicated team in restoring the locomotive for static display, an important task as its centenary approaches.”

The museum has expressed its thanks to Coal and Allied, Port Waratah Coal Services and the Dick and Pip Smith Foundation as major sponsors of the project.

The completed locomotive will be unveiled at the museum on Saturday morning in the presence of sponsors, local dignitaries, former locomotive crew members and museum volunteers.

The unveiling ceremony will include military re-enactors and a display of militaria.

The public is welcome to view the ceremony, which will start at 11am.

Coalfields Steam will continue on Sunday and Monday, with other attractions including a vintage farming machinery display, miniature steam train rides, model railway layouts, miniature steam engines, model boat displays and vintage trucks.

Admission to the museum is $16 adults, $11 concession, $7.50 children five-to-15 years, with children under five free. Unlimited steam train rides are included in the admission charge.