Hard rock needed for building has always been in short supply in the South East of England so Kentish Ragstone, the only significant source of hard rock in the region, has been in demand since the Roman times.

The Romans made significant use of Kentish Ragstone in their buildings and some 45,000 tonnes, quarried near Maidstone, were used in the building of the walls of Londinium (London) to protect the city. The rocks were transported by barge along the River Medway to London. A Roman ship discovered at Blackfriars in 1962 had a cargo of Kentish Ragstone, probably from Maidstone, on board. It is possible that the first settlement in the Maidstone area in the Roman times may have been as a result of the quarrying of Kentish Ragstone. Two Roman villas found in the area, one at The Mount just to the north of the Maidstone East railway line, and another south east of the Conservation Area on the eastern side of Upper Stone Street in Maidstone, have links with quarrying and a settlement could have arisen for those working in the quarrying and shipping industries.

The use of the stone continued in the Norman period and Westminster Abbey, the Tower of London, the White Tower in London, and Leeds and Rochester Castles in Kent were all constructed using Kentish Ragstone. During the construction of Westminster Abbey, vast quantities of Kentish Ragstone were required so a royal command decreed that "no Kentish Ragstone shall be carted to London for any other purpose until the Abbey is built". Kentish Ragstone was also used to make cannon balls: in 1419 King Henry V ordered 7000 of these from Maidstone quarries.

Knole HouseExamples of historical buildings in Kent that were constructed with Kentish Ragstone include the Archbishop's Palace in Maidstone, Westgate in Canterbury, the keep at Dover Castle, Knole House, Ightham Mote and Maidstone Prison. Most of Kent's medieval parish churches were also built of Kentish Ragstone. It is the most utilised hard rock within Kent and is commonly seen throughout the county, particularly in houses, walls and churches.

Gallagher continues this tradition by supplying stone for the restoration and repair of historical buildings, thus ensuring that the repairs blend in with traditional Kentish Ragstone.