Christian Verhounig, the line’s chief executive, said Lupino was "an essential member of the team" which launched the company and a "long-term friend".
“In these moments, the overriding feeling is one of utter shock, disbelief and sadness, but I hope in time the sadness will make way to gratitude – gratitude for what a fantastic, vibrant character and valued colleague, business partner and friend Michelle has been to us all," Verhounig added.
"Her extreme dedication, attention to detail and creativity have played a big part in us being where we are today, and she will be greatly missed by all at Ambassador and her many friends in the industry."