David Pilling Software was in business between 1988 and 2023, the bulk of the activity was in the 1990s on the Acorn/RISC OS platform. Trading ceased in May 2022 and David Pilling Limited was listed as dormant at the end of January 2023.
These pages make the software available for free along with source code. If you just want ready to run software, it is here, but you may have to download an archive that also contains source code to find it.
The Software Build page explains the history and how to go about building the software from the source code.