Although the connection might at first seem incongruous, the tunnel’s recently revealed history as a storage site for chemical weapons during World War II made it an ideal subject for the History Channel series, Cities of the Underworld.

Presenter Don Wildman filmed segments for the episode earlier this month, providing an interesting diversion for Sunday morning shoppers in Glenbrook village before interviewing two former RAAF armourers at the old railway tunnel.

Now used as a mushroom farm, the tunnel housed enough mustard gas to wipe out the population of Sydney during World War II. Bound to secrecy at the time, the men who worked there only gained widespread recognition this year following the publication of a book on Australia’s chemical warfare history by author Geoff Plunkett.

Eighty-four-year-o ld Penrith resident Geoff Burn was happy to be involved in the History Channel documentary although he is still stung by the lack of official acknowledgment successive governments have shown to the young men who carried out the dangerous work at Glenbrook.

“I look at it as if it’s too late . . . We waited over 60 years to get any sort of recognition whatsoever — before that we didn’t exist,” he said.

Mr Burn was joined in the series by 83-year-old Gerringong resident Arthur Lewis who swapped his family’s Parramatta home for a masonite hut at Glenbrook during the 1940s.

The History Channel’s small LA crew also filmed segments at Cockatoo Island, Middle Head and the Abercrombie Caves during their Australian sojourn.

The episode on the Glenbrook tunnel will air in 2009.