Local bricks - 'Fisherton Greys'
These are Fisherton Grey bricks. They were hand-made from a local chalk clay, a “brickearth” alluvium along the north side of the Nadder, giving them a red or cream to grey colour depending on oxidisation or reduction in firing. 
There were several pits and works along the Wilton and Devizes roads and the St Paul’s area where they meet. There is a Brick Lane near the Skew bridge on the Wilton Road and The Hardings off Devizes Road is named after the main brick making family.
They were made from the 17th to 19th C.
Fisherton bricks are widespread in Salisbury and the cream to grey ones are seen in the White Hart Hotel, the Guildhall and the 19th C railway station buildings (though not the 20th C front range).
Fisherton Greys were used here in Stratford sub Castle when the school was built in 1840. It was enlarged with a different batch of Fisherton grey bricks in 1906, a year after this photograph.
Also the late 18th C rebuild front of the Parsonage and parts such as most header arches above the windows and some of the street facing wall of the Old Laundry and just outside the village, the E shaped Avon Farm Cottages.
Photo of school 1905 by kind permission of the Wiltshire and Swindon History Centre.
 Wright, J. In Old Bricks - history at your feet. Futcher, Salisbury. https://www.brocross.com/Bricks/Penmorfa/Pages/england8.htm
 P M Hopson, A R Farrant, A J Newell, R J Marks, K A Booth, L B Bateson, M A Woods, I P Wilkinson, J Brayson and D J Evans. Geology of the Salisbury Sheet Area. British Geological Survey Internal Report IR/06/011 © NERC copyright 2006 Keyworth, Nottingham, British Geological Survey 2006 Page 185
 Wright, J. In Old Bricks - history at your feet. Harding https://www.brocross.com/Bricks/Penmorfa/Pages/england10.htm