The chancel and porch of St Peter's Church in Horninghold are roofed in Collyweston slate. The lifespan of both these roofs, which had previously been re-roofed in 1836, came to an end in late 2025. Thanks to the tireless work of the PCC and with support from the National Lottery Heritage Fund and other grants, these roofs were subsequently replaced with new slates from the Collyweston mine. This work was completed in February 2026 and was undertaken by Richard McCrone of Laxton, Northamptonshire.

There are various parts of the country where local stone is used to provide slates for roofs, including Lancashire, Yorkshire, the Cotswolds and Dorset. In the East Midlands, the primary source of quality limestone slate is from seams mined between Collyweston and Easton-on-the-Hill in Northamptonshire.

Stone log blocks were extracted from open-cast quarries, or later shallow tunnels, watered and left outside in winter to allow the frost to split the stone to form thin slates. These would then be 'clived' by craftsmen into different sizes for the laying of roofs. The biggest slates were laid first at the bottom and from there the size of the rows would gradually diminish towards the top. Each slate has a specific size and name which are listed below, starting with the largest at 835mm (Long Ten) to smallest at 115mm (Outrule). There are 28 sizes in total.

Archaeological evidence shows that the Romans used the slate in the form of a diamond with a peg hole at the top. By the medieval period, production was sufficient to supply 14,000 slates to Rockingham Castle between 1375 and 1390. Roof structures were of oak with square section rafters to support the heavy slates and battens made of riven oak or chestnut. Slates were hung from the battens by oak pegs. The underside of the roof was covered with a soft mortar made of lime and hair, called torching, which helped weatherproof it.

Collyweston slate roofs can be found in towns and villages across the region. Stamford has an outstanding selection, while they can also be seen at Cambridge colleges, including King's and Clare, and in London, for example at the Guildhall in the city. Collyweston was even used at Westbury House in Long Island, New York, which appeared in Hitch, starring Will Smith, and Alfred Hitchcock's North by Northwest, featuring Cary Grant.

Mining ceased in the 1960s as climate change reduced reliable cold conditions for splitting the stone. After Sheffield Hallam University and Historic England developed a new freezer technology to produce new slate to re-roof Apethorpe Palace, Claude N. Smith Ltd. re-opened  a mine in 2016. It is this mine which supplied slate for St Peter's Church.