Shell, Marriott and H&M are among the blue-chip customers of this Manchester firm, which serial entrepreneur Brendan Doyle, 54, spun out of another of his businesses in 2013. CMSPI offers consultancy services to large merchants, helping them to optimise and reduce the costs of payments — which can be its clients’ third largest expense. It has opened an office in Atlanta to service its US clients, helping international sales climb to £2.3m last year.