What was one of the popularizers of the slogan "the customer is always right" also known as?
The customer is always right: "The customer is always right" is a motto or slogan which exhorts service staff to give a high priority to customer satisfaction. The customer is always right:  It was popularised by pioneering and successful retailers such as Harry Gordon Selfridge, John Wanamaker and Marshall Field. Harry Gordon Selfridge: Harry Gordon Selfridge, Sr. (11 January 1858 – 8 May 1947) was an American retail magnate who founded the London-based department store Selfridges. Harry Gordon Selfridge:  He was known as the 'Earl of Oxford Street'.
the 'Earl of Oxford Street'