This is a low-profile firm operating behind the scenes providing power to events such as the Olympics and the World Cup, or to keep the lights on in developing countries. Often the only evidence of its presence is a discreet badge on the side of the generators produced at Dumbarton.
At its helm was a former disc jockey with an aristocratic bearing and the penchant for a neat phrase that seems to come so easily to members of the Soames-Churchill clan.
Mr Soames's networking talents opened doors for Aggreko at a time when the gap between the world's power needs and supply, particularly in emerging nations, was expanding rapidly. Much attention will be paid to the challenges he faces at Serco, a FTSE-250 company with a market worth less than half that of Aggreko but a much higher public profile.
But whoever takes over the helm at Aggreko also has a tough task due to the faltering of the developing market growth that has been central to its expansion.
Aggreko had two profit warnings in 2012. Performance in 2013 was muted by the ending of tsunami-related work in Japan, the withdrawal of troops from Afghanistan and the absence of a major sporting event.
Chairman Ken Hanna insisted yesterday: "The fundamentals of a growing gap between global power demand and power supply is as strong as it has always been."
Any successor is unlikely to have Mr Soames's unique communication talents but he or she will have to convince investors that Aggreko's future is as bright as its last decade.