The Mansion as it now stands was commissioned by Washington Jackson. When he bought the property from Henry Spencer in March 1862 there must have been a house there already. Its probable location was due west and adjacent to the present house. Jackson, still a bachelor at that time, lived in it for over a decade.
Edmund Cropper had asked Waterhouse to survey the estate in 1857. Henry Spencer used an unknown builder, but in 1871, when Jackson was ready for his grand house he chose Alfred Waterhouse. The first design was prepared in 1871-1873. This was set aside in favour of another, quite untypical, which was built and which remains largely unchanged. The service wing was a linked building on the east side. The impressive 120ft x12ft high brick wall with stone coping was probably built on the west side where the first house stood in order to give the whole concept a balanced appearance.
The wealthy late Victorian clientele wanted a house to be substantial, serious, dignified but not ostentatious. It was designed for family life and entertainment of friends. It had to be comfortable, but not luxurious. Decent quarters for servants was a necessity. In the 1870s a house of this nature would have had five indispensable rooms: viz: billiard room, breakfast room, morning room, drawing room and conservatory. One of the rooms in Town Thorns was certainly a billiard room, and the conservatory is clearly visible on the photographs.
Victorian conservatories were for winter flowering and foliage plants, ferns and fragile exotic flowers. To create this artificial environment, they had to be heated. Hot water and heating systems were known and it is highly probable that there was a vast boiler somewhere in the building. It was quite usual for the conservatory to open into the drawing room. This room tended to be in the southeast corner in order to get the morning sun. It was the room where the lady of the house would receive her visitors. It is now the Chapel.
A freestanding tower, probably an extension in the 1880s, seen on the old photographs housed a cistern. It is likely that water from underground was pumped by a steam pump to maintain a constant supply.
Plumbing and water closets were available from the beginning of the Victorian era. By the 1870s there were separate bathrooms. Previously, baths were a luxury. Portable baths, hipbaths, footbaths and hand filled basins were set up in the bedrooms by the fire. Maids or men-servants would have to bring up jugs and jugs of hot water. Afterwards the water would have to be emptied and carried down. When the first bathrooms were incorporated, cold water was piped, but the hot water still had to be carried up. Waste pipes were a later addition. Washbasins were not common and the crockery jug and basin stood on washstands. The Americans had adopted en-suite facilities, each bedroom having its own bathroom. Washington Jackson, being familiar with this trend might have asked for his house to be provided with the same, although, by the layout, the plumbing was probably confined to the north side. The ratio of bathrooms to bedrooms might have been 1:3
Central heating was, at best partial, mainly installed in the hallways and corridors. The preferred method of heating and ventilation was the open fire. The chimney pots, still visible on the rooftop, are evidence of the quantity. The principal rooms at Town Thorns would have originally featured magnificent fireplaces with ornamental ironwork and chimney pieces of marble and decorative tiles. None of these remarkable features have survived the removal of all the fireplaces in the Mansion.