A painter in Tasmania has uncovered a sealed glass bottle containing a message that was hidden within a wall cavity of the historic Cape Bruny lighthouse more than 120 years ago.

Specialist painter Brian Burford was performing routine maintenance on the seaside structure when the discovery took place, according to Annita Waghorn, historic heritage manager for the Tasmania Parks and Wildlife Service.

“While he was working inside the lantern room – which is the room at the top of the lighthouse where the lens and lightening mechanism is – dealing with some rust and corrosion, he popped through into the wall cavity,” Waghorn said.

It was then that something in the cavity caught Burford’s eye, “glinting” in the light.

“He was so excited that he gave me a call and said that he found a message in a bottle,” Waghorn said.

It turned out that the letter was not just a simple note, but an envelope containing two hand-written pages detailing upgrades made to the lighthouse in 1903.

A staircase, floor, lantern room and lens were added to the heritage-listed lighthouse nearly 70 years after the original structure was built in 1838.

The note was signed by lighthouse inspector for the Hobart Marine Board, JR Meech, who supervised the construction and maintenance of several well-known lighthouses around Tasmania including Cape Sorell, Maatsuyker Island, Tasman Island, Table Cape, and Mersey Bluff.

“It was incredibly exciting … it was such a mystery when it first came to what the message was about and how it had come to be in this inaccessible location within the tower,” Waghorn said.

But it wasn’t an easy feat. Initially reluctant to open the bottle, Waghorn enlisted help from conservators at the Tasmanian Museum and Art Gallery who carefully extracted the delicate aged paper.

“The bottle was sealed with a cork coated in bitumen, which made removal challenging,” Cobus van Breda, the museum’s senior paper conservator, told the ABC.

“We had to remove the bitumen from the top of the cork, then carefully work our way around the cork to detach it from the glass as the cork had been dipped in bitumen.”

“The next challenge was to get the message out of the bottle. It had been folded in a way that made it quite challenging to get it through the narrow neck of the bottle without damaging it.”

It took several days to decipher Meech’s message, the team said.

Museum staff plan to put the letter on display for public viewing.