It was the discovery in 1970 of the arcade at the low end of the hall that puts the building among the rarest of the rare. The hall itself is dated to the 13th century chiefly by the two cross frames which support the roof with scissor-braces (or more correctly passing-braces). They were a form widely used in manorial houses between 1150 and 1300 and recorded examples, although growing in number, are still few. This is not just because of their great age, but also because around 1300, this construction method was superseded by arch-bracing and crown-posts both on grounds of taste and of greater strength. Most early halls were rebuilt, or were altered in one way or another, and survive only as fragments, as here.
To summarise what happened at Purton Green, the walls and north end were rebuilt soon after 1400, and the south end was rebuilt about 1600. At the same time, as in nearly all small medieval halls, an upper floor and chimney stack were inserted, and all signs of early origin vanished from sight for over 300 years. In 1970, these later additions were removed to reinstate the open hall. But it is one of the joys of visiting such a building to decode it for oneself, and so the main phases are given in more detail below.
A new house is built, possibly by Walter de Priditon, Steward to the Earl Marshal, who held the manor of Priditon or Purton Hall in 1275. The house was timber- framed, with a thatched roof, its central open hall about thirty feet long. An open truss, strengthened by passing-braces, stood half way along to support the roof. The rafters continued beyond the main posts to cover 'aisles' on either side, making the hall nearly as wide as it was long. An open hearth stood in the southern half, and smoke escaped through vents at one or both ends of the main ridge of the roof. A second, 'closed', truss at the north or low end of the hall formed a partition between it and a probably two-storey end bay, with pantry and buttery on the ground floor and sleeping space above. In the lower part of this partition was an arcade of six arches, three blind and three with doors. At the south or high end of the hall there may also have been private rooms for the owner's family, but evidence for them has been lost in later rebuilding.
Outer walls were rebuilt some two feet inside the old for greater height, reducing the width of the aisles, and of the outer arches of the arcade in the low end partition. The north end upper floor was rebuilt and extended with a jetty, and the roof altered to give more headroom. The partition between the low end and hall was plastered, arcade mutilated and covered up, a stair built in one of the central doorways, and a plaster flue introduced above the collar to take smoke from the hall.
Purton Green now a farmhouse, if a prosperous one. A floor is inserted into the open hall, and a chimney built just south of the central truss. A new front door enters to a lobby beside the chimneystack. The entire south end is rebuilt, with a parlour on the ground floor, which had a projecting oriel window. As at the north end, the first floor area was increased by means of a jetty.
18th century and later
From before 1780 until the late 19th century Purton Green Farm was occupied by the Pratts. Gradual updating of the interior, walls were replastered, new fireplaces installed, front doorcase and door, and windows were added. The chimney was added at the north end. A wing added on north-east corner is not shown on the 1840 Tithe Map, so this is presumably later.