The story began in France, England, and Spain where Guillaume passed the Bac leaving exams at the Lycée Français de Madrid after 15 years of living abroad. He went on to complete a Bachelor's degree in International Management at ESC Clermont earning a double degree in Emerging Markets Management at the Universidad ESAN in Lima, Peru.
When he returned to France, he decided to enter KEDGE's Specialised Master in International Business on its campus in Bordeaux. He worked for the multinational company Danone Waters as a sales manager for the Corsica region during his 1st-year internship. There he developed close relationships with the major retailers in a very competitive market mainly dominated by local water companies such as Saint Georges and Orezza.
Aware of Thailand's growing importance in the South East Asian economy, Guillaume went to work for Luma Care, a wholesale broker specialising in international health insurance, based in Bangkok and managed by Paul Dominique Vacharasinthu. Starting off with a six-month internship as part of the business development team, he was hired as a key account manager at the end of his internship. In that position, Guillaume was in charge of developing the group's image and the portfolios of clients in Thailand, Cambodia, Vietnam, Myanmar, and Laos.
In 2019, he was promoted to distribution manager and continued to gain expertise in personal insurance when he managed the company's product development department.
In 2022, Paul Dominique and Guillaume began the expansion of the Luma Group in Europe, and more specifically in France, with the launch of Insuneo, a digital insurance brokerage company specialising in insurance solutions for individuals and small and medium-sized businesses.