Sir Donald Bradman's first baggy green is currently being auctioned online through pickles.com.au

The auction started on December 10, and the cap to be knocked down tonight at 7.30pm AEDT.

At the moment the leading bid is $379,000

Sir Donald was presented with his first baggy green (#124) in November 1928 for his Test debut against England, in Brisbane.

In 1959 he gifted the baggy green to his neighbour, Peter Dunham, whose house backed onto the Bradman's family home on the Parade in Kensington Gardens.

The baggy green has been on loan to the State Library of South Australia since 2003 and has been authenticated by former manager of the State Library of South Australia's Bradman Collection, Barry Gibbs.

Dunham, an accountant, was in May this year jailed for eight years and two months for scamming $1.3 million from his investors.

Some of Dunham's victims sought access to Bradman's cap to help pay off the accountant's debts.

Dunham faced the South Australian District Court initially charged with 37 theft and deception charges spanning 2008 to 2015.

Just before his trial, Dunham, now aged 76, pleaded guilty to many of the charges on the condition others were dropped.

The court was told Dunham had repaid about $800,000.

District Court Judge Paul Muscat described Dunham's offending as calculated, deliberate and repetitive and imposed a non-parole period of four-and-a-half years..

Dunham's estate was bankrupted, with Bradman's cap to be sold on Thursday under instructions from the trustee, Oracle Insolvency Services.

The baggy green cap has been on display for the past 17 years, loaned by Dunham to the Bradman collection at the State Library of South Australia.

Bradman's Test debut cap is listed under the Cultural Heritage Act and can't be removed from Australia.

History shows it was a less than inspiring start for the man now considered to be the best batsman of all time, with a Test average of 99.94

Bradman made a collective 19 runs in that Test - 18 in the first innings and just one in the second, showing very little for the man who would go on to an amazing career.

He was dropped by selectors for the second Test.

He returned for the third Test and went on to play 52 Tests, scoring 6996 at an average of 99.94 with 29 hundreds and 13 half centuries with a top score of 334 (452 not out in first class matches).

It's been a big few weeks for Bradmanophiles, with the cricket pitch linked to Sir Donald Bradman in his youth been saved from development.

Developers had applied to build a seniors' facility on the land in the NSW Southern Highlands town of Bowral.

But the NSW Land and Environment Court refused a development application on land where the cricket pitch is located.

Historian and keen campaigner for the preservation of the site Nick Corbett said was thrilled with the outcome.

"It's fantastic news. It's been a long hard fight for sure and great to be able to celebrate a victory," he said.

The record price for an Australian baggy green is Shane Warne's Test cap which fetched $1,007,500 when purchased by the Commonwealth Bank in January.

Warne sold his cap to raise money for bushfire relief, with the bank taking the cap on a national tour before becoming a permanent exhibit at the Bradman Museum in Bowral, NSW.

with Australian Associated Press