The NewBrain project started in 1978. Sinclair Radionics began working on a project with Mike Wakefield as designer and Basil Smith as the software engineer. The intention was to compete with Apple. However, when Sinclair realised that the NewBrain could not be made for under £100 he lost interest, failing as it did to meet his focus on inexpensive consumer-oriented products. He turned instead to the ZX80 that was developed by his other company, Science of Cambridge Ltd.

Following the closure of Sinclair Radionics the NewBrain project was moved to Newbury Laboratories by the National Enterprise Board (NEB), the owner of both Sinclair Radionics and Newbury Labs. In 1980 Newbury announced the imminent release of three NewBrain models, including a battery-powered portable computer. In August 1981 Newbury Labs sold the project to Grundy Business Systems.