Pure speculation

By the 1860s, deep lead gold mining was well under way along the Leigh River. In 1863, it came to the Leigh Grand Junction in the form of the Leigh Grand Junction Mining Company who set up operations only a few hundred metres upriver from the site at which the bridge of the same name would be built in 1873 - see this post.

[I have not seen an explanation for the origins of this name, however as the mine precedes the bridge, I am guessing the bridge took its name from the mine or from an earlier, unknown source. Perhaps the name reflects the proximity of the area to the boundaries of the Shires (earlier known as Road Districts) of Leigh, Buninyong and Meredith. A grand junction of the shires!]
The Leigh Grand Junction Mining Company was registered, according to the Victorian Government Gazette of 27th March, 1863 under that name. It was located on the "Durham Lead, adjoining the City of Manchester (mine) and Mr Bell's private property". It launched with limited liability and nominal capital of £10,000 - of which £100 had been paid. The mine manager was Joseph Frederick Bowes.

Mullock heap remaining in the vicinity of the Leigh Grand Junction Mine

A different view

Initially, six hundred shares, each valued at £16/10/4 were issued. Throughout the year there were "calls" for shareholders to pay part of the capital owing on those shares - the means by which mining companies financed their operations. The calls however were regularly followed by threats of legal action if payment dates weren't met. Things began to progress for the Leigh Grand Junction Mining Company in January, 1864 when tenders were called for carpenters, masons and foundry men to erect a 20.5 inch cylinder, horizontal steam engine with pumping and winding gear included.

Remains of a boiler at the site of a gold mine on Woodbourne Creek, similar
in size to that ordered by the Leigh Grand Junction mine

The company continued to make calls upon its shareholders throughout the year and in October - presumably in a bid to raise more funds - a new deed of partnership was drawn up, the old shares revoked and 4,200 new shares issued, each valued at £9. The mood seems to have been optimistic throughout 1865 and by June a break through to the auriferous "gutter" was expected at any moment. As the year progressed however, the calls upon shareholders continued, as did the drilling.
By September, the shaft had reached a depth of 246 feet (75m) below surface level and it was decided to continue to a depth of 267 feet which it was felt would be adequate to reach the wash dirt.
Funds however, were still an issue. In August, 1865 just a month before the decision to drill deeper, the 31st call was made and notice was given of an Extraordinary General Meeting to be held the following January whose purpose was to "empower the directors to borrow money on mortgage of the plant and claim of the company". William Auld was now acting as manager pro tem.

Shaft entrance and diggings at or near the sight of the Leigh Grand Junction Mine

By November they claimed to be mere feet away from the gutter, however success was still not forthcoming. The outcome of the January meeting does not appear to be mentioned in the media however, in February, 1866 the company was temporarily forced to stop work due to lack of capital.
Throughout 1866, the company continued trading - a statement of their financial position appeared in the Victorian Government Gazette of July 31st - and another meeting of investors was held on 15th September at which the company's directors were given the power to take out a larger mortgage to the value of  £2,000. The general mood was one of optimism and it was noted that nearby surface claims being worked were paying well, so there was an expectation that the Leigh Grand Junction Mining Company would soon turn a profit too. The mortgage, along with money owing from "unpaid calls" it was felt, would soon allow mining to recommence and when it did, there was only 50 foot of rock to be drilled through to reach the gutter, at which point, washing of the dirt could immediately commence as the puddling machinery to do the job was already in place.
In fact, by 18th December, 1866 this seems to have been the case. A general meeting of shareholders held (as usual) at the North Grant Hotel in Ballarat, was informed that the mine's equipment had been completely overhauled and that the engine which had previously operated at 50lb pressure was now working at 25lb, meaning a significant saving in the amount of wood required to fire it. Their finances were in good order and they expected to be in the gutter in six weeks, contractors having already removed 10 feet of "reef" during the earlier part of the month. Things were looking up.


19th century sketch of the North Grant Hotel. Image held by the
Gold Museum, Ballarat

Progress continued into 1867 with a "reef drive" being extended by 20 feet. More bores were also sunk to drain the workings which were reportedly producing water at a rate of about 800 gallons/hour. Finally in March, 1867 a breakthrough occurred and the Australasian reported "The upper-drive workings of the Leigh Grand Junction Company have broken into three feet of washdirt. The reef is nearly level and gold is just visible."
Any optimism following the breakthrough was short-lived as the gold extracted from the claim was still not enough to keep the operation afloat, let alone return a dividend to shareholders. By late September, the works were again on hold "for want of calls" and the company's liabilities were approaching £900.
And so the cycle continued into 1868. Works were continuing in the first months of the year with the manager listed as J McQuie, who had held that position since 1866, but by April things had reached breaking point. A meeting was called for 2nd May, to decide whether to continue operations or to pay off the company's liabilities and wind it up.

A gold mine from the Northern Territory which may have been similar in scale
to the Leigh Grand Junction mine, image held by the Northern Territory Library

By May it was all over. A mortgagee sale was to be held at the end of the month to sell off, the claim and its associated equipment. This was followed by a second auction on the site of the claim in July. At the same time, the trustees of the company were summonsed to defend a claim by Robert Allan of Buninyong who asserted that claim number 917 (known as the Leigh Grand Junction Mining Company) was abandoned and that by virtue of miner's right he was entitled to take possession and occupy the claim.
Finally, in February 1869, tenders were called for the removal and re-erection of a large pumping plant which had recently been purchased from the Leigh Grand Junction Mining Company. The venture had come to an end.
Throughout the ensuing decade, there was little activity recorded in the area. It was noted some years later that "The yields from the Leigh Grand Junction claim, though poor, were not of so utterly discouraging a nature as to prohibit further enterprise, and an increase is not less probable than a diminution of yield as the lead travels south."
A report in 1874 indicated that although the claim was idle, good gold could still be obtained. It was stated that previous operations at the site had been abandoned due to a lack of funds before the deepest part of the gutter was reached.
This was not quite the end of the gold mining history of this site however and it may have been reports such as these which in 1887 led to resumption of mining operations on the site.
The Victorian Government Gazette of 28th October, 1887 records the registration two days earlier of the Madame Bent Extended Gold Mining Company, with Benjamin Doughty Smith as manager, issuing 24,000 shares valued at £2 each.
This company is not to be confused with the similarly-named (and possibly more successful) Madame Bent Mining Company which was first registered a year earlier in October, 1886. According to the prospectus for the latter company (published in the Argus 27th September, 1886), this mine operated from what had previously been the City of Manchester Mine, the neighbouring claim located a short distance upriver from the old Leigh Grand Junction Mining Company claim.

Section of map showing the relative positions of the Leigh Grand Junction
and the City of Manchester mines as indicated by the letter X. Full image
held by the State Library of Victoria

There have been various sources over the years, some of which indicate - accurately - that the Madame Bent Mining Company was formerly the City of Manchester mine, however there are just as many indicating that it was previously the Leigh Grand Junction Mining Company. I suspect that the two companies were not unrelated as it seems likely that BD Smith, auditor for the Madame Bent Mining Company in 1886 was the same person as Benjamin Doughty Smith, manager of the more-recently established Madame Bent Extended Mining Company, which was launched the following year - perhaps on the back of the projected success of the earlier mine.
Regardless, the mine at the Leigh Junction is mentioned only three times in the government gazettes from this later period and there is no online reference I can find later than mid-1888 which might indicate the success or otherwise of this mine. I can only speculate that perhaps it was wound up at the same time as the original Madame Bent claim.