Castleton Technology plc, formerly Redstone PLC, is a United Kingdom-based investment holding company. The principal activity of the Company is the provision of software and managed services to the public and not for-profit sectors, mainly the social housing sector. The Company's operating segments include Managed Services, which consists of the results of Montal Computer Services Limited (Montal) and Keylogic Limited (Keylogic), and Software Solutions, which consists of the results of Documotive Limited (Documotive) and Opus Information Technology Limited (Opus). Montal is an information technology (IT) managed services business. Documotive and Opus are specialist software providers to the social housing sector. Keylogic is an infrastructure managed services provider with a focus on the social housing sector. The Company's subsidiaries include Castleton Technology Intermediate Holding Company Limited and Redstone Group Holdings Limited.