Minimbah (Cobb) can be seen on the lower left of the map below adjoining the estate of Castle Forbes.
ARRIVAL IN THE COLONY
John Cobb was recommended as a free settler and arrived in 1823 on the Francis with his wife Maria. Hunter Valley settler John Eales also came on the Francis.
After supplying a statement to the authorities regarding the number of convicts he could support off the Stores,John Cobb was granted 2000 acres and six convict servants. A town allotment in Newcastle was reserved for him in 1824.
MINIMBAH AND RUSHOLME
His estates at Patrick Plains were Minimbah and Rusholme although he resided and farmed at George Cobb's estate Anambah.
George Sparke was employed at Minimbah as station manager in 1833. 
In 1838 John Cobb was advertising to let a house for use as an Inn at Minimbah as Benjamin Levien had broken his agreement.
John Cobb died on 7th April 1840 aged 37 and in 1841 Minimbah was advertised to be let for a term of seven years:
That most splendid estate called Minimbah near Patrick's Plains, possession to be given on 1st March next. This Estate is situated at Darlington adjoining the celebrated Estate of Castle Forbes; the high road to Jerry's Plains, Merton and the Upper Hunter district, running through the property and within four miles of the flourishing town of Singleton. The Estate is well watered the Minimbah Brook running through it. It contains six thousand acres, has excellent pasturage and plenty of good land for cultivation. There is a cottage, stock yards, mens' huts and other conveniences already erected. For further particulars apply to William Innes at Hinton. 
In the 1850's Robert Adamson Rodd the son of John Tremayne Rodd resided on the Minimbah estate.  Minimbah estate was acquired by the family of Duncan Forbes Mackay in 1871.
In 1875 - 1877 Minimbah house was constructed for the Mackay family. A correspondence to the Maitland Mercury described the building during construction....
Amongst the various buildings now in course of erection in the Singleton district, the most important and extensive is, without doubt Mr. D.F. McKay's splendid new mansion at Minimbah. A very excellent site has been chosen for the building on an elevated plateau about one and a half miles from the Whittingham platform, on the G.N Railway, or four and a half miles from the town of Singleton. Most charming views will be obtainable from the upper story of the mansion. In front are the valuable estates of Baroona and Neotsfield, encircled by the waters of the Hunter; and beyond that river may be seen the rich agricultural flats on its banks, with the Tangorin and Mirannie ranges in the far distance.
To the right, in the immediate vicinity, is the old Minimbah House, about half a mile distant, with the various sheds and cultivated lands surrounding it, forming a pretty picture. Beyond are wooded undulated lands, and the view in this direction is bounded by the high range of mountains from the Yellow Rock at Fordwich and the Rothbury estate towards Black Creek. To the left the rich agricultural lands forming Patrick's Plains proper, with the town of Singleton in the distance present a most delightful view. The Great Northern Railway is only about three quarters of a mile from the mansion, and the latter can now be plains observed by the passengers from the trains. The animation gives to the scenery by the running of trains tens still further to add to its attractiveness. The building will consist of the main building with two side wings, the latter enclosing in the rear a spacious garden court, 50 feet x 40 feet, to be planted with shrubs and flowers, with a fountain in the centre. The mansion will be two storys high. It is built on an excellent foundation formed of the natural bedrock which was reached after an excavation of three feet had been made. On this solid foundation massive walls in brick and cement were carried up to a height of eight feet to the base course, from the base to the first floor the walls are eighteen inches thick and from the first floor to the roof 14 inches. The ceilings on the ground floor are fourteen feet high, and these on the first floor thirteen feet. The roof will be very strong, the principal timber being 5 x 2 1/2 inch hardwood rafters; these boards will be covered with layers of thick felt which will be battened, and slates completing the whole.
An idea may be formed of the size of the building when we state that the height of the ridge of the roof will be fifty feet fro the ground floor, and that about 650,000 bricks will be used in its construction. These bricks are principally made on the estate but a few are obtained from Maitland to be used in such portions of the building where extra strength is required, such as arches and round openings etc. the Maitland bricks being superior to any made in this district although those made on the Minimbah estate appeared to us to be of very fair quality. The whole exterior of the building is to be cemented. Great attention has been paid by the architect to provide extra strength where required by the introduction of iron girders and due regard has been given to ventilation and drainage the most modern appliances having been introduced in the plans and specifications. The front of the main building will have a noble appearance.
The original design was strictly Corinthian, but this style has been modified (we think advantageously by the abandonment of heavy looking circular brick columns to the colonnades and palings and substituting light, airy and graceful iron columns, filled in which spandrils and frises of ornamental case iron Spacious colonnades and balconies 11 feet wide will run in the front, and on each side of the main building; the colonnades being continued by verandas only to each side wing 3 feet wide. The colonnades and verandahs will have cement flowers with rubbed Ravensfield stone curbs. In the centre of the front will be a pediment carried the whole length of the front; the latter will show fourteen openings. The roof on the main building will be hidden to some extent by a handsome parapet in front and sides, but the roof of the side wings will be constructed with projecting eaves. The windows in the ground floor of the main building, 10feet 6 inches high by 4 feet wide, will be so constructed that the sash can be easily ran up in order to admit a person to walk from the rooms through the casements in to the colonnade, and vice versus. The windows in the first floor of the main building are of a similar size but will be constructed in the ordinary manner.
On entering the front door of the main building we find a spacious hall, 36 feet long by 19 feet wide, from whence a noble staircase leads to the apartments above. On one side is the drawing room 31ft x 20 and on the other side the dining room of the same size. At the rear of the dining room is a breakfast parlour, 16ft x 16ft and a serving pantry 16ft x 13 ft. communicating with both; and a passage 5feet wide running along the whole width of the main building at the rear and thereby facilitating access to both side wings. At the rear of the drawing room is the library 16ft x 16 feet and another room 16ft x 14 feet. Ascending the spacious staircase we find the landing 23ft long and 19 ft wide, and from thence we enter the bedrooms on the first floor of the main building which consist of two best bedrooms each 22ft x 20 ft, a dressing room 15ft by 9 ft being attached to each; also 2 bedrooms each 18ft x 16 ft and 2 bedrooms 14ft x 12ft. On the ground floor of the right wing is a pantry 14ft x 10 ft kitchen 24 ft x 18 ft., scullery 12ft x 6 ft., laundry 18ft x 15ft., and on the first floor of the same wing entered by a separate staircase are two bedrooms 14ft feet x 14 feet with closets attached, a third smaller bedroom at the end of the wing a room to be devoted as a Turkish bath room. This room is situated immediately over the laundry, and it will be heated by the boiler in that apartment. The walls of the Turkish bath, and of the other bathrooms in the building are strengthened by iron girders with concrete floor. On the ground floor of the left wing is the billiard room 28 ft x 18 ft, the dairy 18 ft x 13 ft, and a storeroom 18ft x 15 ft. Under the latter is a spacious cellar with a concrete floor, and supported by arches and ceiled with concrete.
The dairy is also made of concrete. On the first floor of the left wing is a schoolroom, governess' bedroom, bathroom and closet and a man servant's bedroom. The first landing of the principal staircase leads through an arch to the conservatory, showing a half circle front to the garden court from whence it is lighted by five windows fitted with ornamental and coloured glass. To the right and left of the conservatory are ladies' bath rooms etc., entered by private approaches communicating with the bedrooms; and underneath at the rear of the hall is a gentleman's closet and lavatory.
Altogether there are twenty eight apartments in the mansion and the exterior walls are pieced by not less than 133 openings. Most ample provision has been made for an adequate water supply even in the direst season. At the side of the right wing and towards the rear of the building an enormous underground tank ahs been constructed. This tank runs in a line with the outside wall of that wing, which constitutes one of the walls of the tank. It has been most solidly constructed of 18 inch brickwork built in cement; it is cemented throughout and subdivided into six chambers by arches, the whole being domed over and coke cemented. This great underground reservoir is 34 feet long by 23 feet wide and 14 feet deep and on descending into it we felt almost as if entering one of those grand old cellars of mediaeval buildings now so seldom to be met with in Europe. This tank will hold about 55, 000 gallons. Another tank constructed of iron over the conservatory will hold 5000 gallons; and the water after being forced up from the underground tank will from here be distributed by means of pipes throughout all parts of this extensive building.
Considerable progress has already been made with brickwork - some 6 portions of the walls requiring only about 3ft 6 inches more in height to be completed. The contractor hopes to have the building out of his hands shortly after the end of this year. The architect of this noble pile is Mr. Benjamin Backhouse of Belmore Chambers, George St. Sydney and the contractor is Mr. Henry Noad of East Maitland- Maitland Mercury 9 June 1877
Two years later a visitor reveals that although construction of the mansion was completed, it was yet to be furnished.....
I had heard a great deal of Mr. Duncan Mackay's new house at Minimbah, and. was well pleased when, in response to a kind invitation from the proprietor, Mr. George Loder said he would drive me that way round to Abbey Green. Arrived at Minimbah, I wasn't at all surprised that people talk in raptures of the new house, for it is quite of the palatial order in point of size of rooms and all modern appliances ; but the furnishing is not yet completed ; and the building has, as yet, to be judged entirely on its own merits, and without the aid of ornamentation either within or without. In case of fire breaking out, a great force of water is available, which in all human probability could be utilised so as to save the whole house from destruction. The entertaining rooms are exceedingly good, the drawing room especially being a credit; to Australia ; and there are a great number of large and lofty bedrooms, which I couldn't help thinking, as I strolled through the house, will want a whole ship-load of furniture, with a perfect phalanx of servants. The former desideratum is easily enough obtained, and satisfactorily, too, no doubt, as I note that Messrs. Bradley, Newton, and Lamb have already made, their mark pretty considerably in the drawing-room ; but the servant element is quite another pair of shoes, the difficulty of finding a good supply of proper "helps" being one of the greatest drawbacks to residence in this fair land.' The house has fine balconies, and commands a splendid view, notably from the top of the tower; whither, I climb at the instance of my companion in exploration, and I was very glad that I did so.
The grounds surrounding this house are not yet laid out, as Mr. Mackay has had many difficulties to contend with by reason of want of rain ; the hard and dry state of the ground which is to be converted into lawn and flower garden precluding all possibility of making grass or seeds of any kind grow in it at the time of my visit. When the house, with its belongings and surroundings is completed, I reckon it will be quite à showplace for visitors to Singleton district. ' Australian Town and Country Journal 2 August 1879
NOTES AND LINKS
1). It is said that Mr. D. F. M'Kay is about to erect a mansion on the Minimbah Estate, in the Singleton district, which is likely to cost £15,000. - Sydney Mail 4 November 1876
2). Minimbah homestead at Whittingham is a 45 room or 3000 square metre mansion, a home that covers one acre of its seven acre block. Designed by colonial architect Benjamin Backhouse, the home was built between 1875-1877 for early Hunter Valley settler Duncan Forbes Mackay on land issued in 1823 to John Cobb....... Select here to find out more about Minimbah homestead.
3). A rear view of the stately and majestic edifice of Minimbah House which at present houses the Aborigines' Inland Mission. The building although suffering somewhat as the result of military occupation is one of the outstanding country mansions of the State - Singleton Argus 2 April 1947
4).Front view of the stately Minmibah Mansion present home of the Australian Inland Aborigines' Mission where Speech Day on Saturday was attended by more than 300 persons a great many of them visitors. - Singleton Argus 24 November 1947
5). Minimbah House - NSW Heritage
 Ancestry.com. New South Wales and Tasmania, Australia Convict Musters, 1806-1849 General Muster 1825: Class: HO 10; Piece: 19.
 Wood, W. Allan., Dawn in the valley : the story of settlement in the Hunter River Valley to 1833 Sydney : Wentworth Books, 1972., p.27
 The Australian 28 January 1841
 Maitland Mercury 10 September 1859