Fears Sydney milestone may 'never see the light of day again'

An innocuous concrete post has been ripped from the roadside, with historian Glen op den Brouw pleading for its return. (ABC News: Simon Amery)

If you passed this slab of concrete in Sydney's south-west, you likely would not look twice, but its rich history has made it a hot target for thieves.

The L4 Mile Peg, with C13 marked on its back, had sat on the corner of Camden Valley Way in Prestons for 70 years.

The L4 was one of the last historic mile pegs that measured the distance between Liverpool and Camden. (Supplied)

The L and four on the post signalled that Liverpool was four miles away, while the C and 13 on the back told drivers travelling southbound it was 13 miles to Camden.

As decades passed, the concrete post, which was once heavily relied on by drivers, became the last surviving marker of its kind in the area — that is, until a local historian noticed it had been ripped from the ground.

Mr op den Brouw shows a photo of the missing milestone, which has C13 inscribed on the back. (ABC News: Simon Amery)

Glen op den Brouw, president of the City of Liverpool and District Historical Society, told the ABC he had spent years endeavouring to have the post recognised and heritage listed.

"I'm still trying to deal with the fact that it's gone missing," he said.

During the 1940s, when the stretch of road was known as the Old Hume Highway, drivers relied on milestone markers such as mile pegs to measure the distance from Liverpool to Camden.

After metrication was introduced in 1974 and wider, newer roads were built, they slowly disappeared in favour of modern traffic signage. However, they still retained significant heritage value.

A truck transporting coal travels along the Hume Highway toward Liverpool in 1949. (Supplied: Transport for NSW)

Mr op den Brouw said he had heard of previous cases in which mile pegs were stolen and later found in someone's backyard.

In other instances, some had been accidentally knocked off the road by heavy vehicles, only for Mr op den Brouw to discover them later rehomed at local museums.

There is now a large hole where the historic mile peg once stood. (ABC News: Simon Amery)

"The first couple out of Liverpool have gone missing …whether somebody stole them or a truck ran into them, and they were beyond repair — I don't know," he said.

Mr op den Brouw said if the peg were returned, there would be no questions asked and "all would be forgiven".

A Transport for NSW spokesperson said it had not removed or relocated the historic milestone marker and that it was "currently investigating and checking with our cont