The company’s investment programme follows a string of recent service centre openings across the UK.
Phase one of the company’s spending spree saw a £2m order placed with Harrington Generators International in the summer.
Gary Orton, director of Mather+Stuart, said: : “Following our acquisition by A-Plant in 2016 we have experienced a period of rapid growth, opening nine new service centres and tripling the size of our fleet from 650 generators in January 2016 to over 2,000 by August 2018.
“To support our expansion plans, keep up with customer demand and ensure we remain one of the UK’s market leaders it is vital that we continually update our fleet.
“With further multi-million pound investments already in the pipeline we can guarantee that we offer the most innovative, reliable, safe, environmentally friendly equipment in the industry.”