The name of the company is mentioned in Kelly's Directory for 1918 and a building plan submitted to Steyning East Rural District Council in 1927, so they were active at this period. They don't appear in the 1930 edition of Kelly's Directory.
The sign at first appears rather plain, with text reading 'A Parsons & Son, Builders & Decorators, Repairs of Every Description'. However, a closer look shows some flourishes attempted in the lettering.