Question: What is the British optical retail chain which has Darren Kennedy as a brand ambassador called? 

Context paragraphs:
Visionworks of America: Visionworks of America, Inc. (formerly Eye Care Centers of America) is an American company which operates or manages 700 optical retail stores in 40 U.S. states and the District of Columbia.  The company was incorporated in 1988.  It is based in Downtown San Antonio, Texas, and has about 5,600 employees.  Before June 2013, when it began operating under the Visionworks name, stores operate under eleven different trade names, including "EyeMasters," "Visionworks," "Vision World," "Doctor's VisionWorks," "Dr. Bizer's VisionWorld," "Dr. Bizer's ValuVision," "Doctor's ValuVision," "Hour Eyes," "Stein Optical," "Eye DRx" and "Binyon's".

Matthew Fergusson-Stewart: Matthew Fergusson-Stewart is an Australian living in Singapore, where he is the Asia Pacific regional brand ambassador for Glenfiddich, distilled by William Grant & Sons.  In January 2017 he was named the "Icons of Whisky" Scotch Whisky Brand Ambassador of the Year by Whisky Magazine.

Brand ambassador: A Brand Ambassador (sometimes also called a Corporate Ambassador) is a person who is hired by an organization or company to represent a brand in a positive light and by doing so help to increase brand awareness and sales.  The brand ambassador is meant to embody the corporate identity in appearance, demeanor, values and ethics.  The key element of brand ambassadors is their ability to use promotional strategies that will strengthen the customer-product-service relationship and influence a large audience to buy and consume more.  Predominantly, a brand ambassador is known as a positive spokesperson, an opinion leader or a community influencer, appointed as an internal or external agent to boost product or service sales and create brand awareness.  Today, "brand ambassador" as a term has expanded beyond celebrity branding to self-branding or personal brand management.  Professional figures such as good-will and non-profit ambassadors, promotional models, testimonials and brand advocates have formed as an extension of the same concept, taking into account the requirements of every company.

James Charles (model): James Charles Dickinson (born May 23, 1999), known professionally as James Charles, is an American Internet personality and model.  On October 11, 2016, at the age of seventeen, he became the first male spokesmodel for cosmetics brand CoverGirl, working alongside brand ambassador Katy Perry.  As the first male spokesmodel and brand ambassador for CoverGirl, Charles will be the face of the soon-to-be launched "So Lashy!"  by BlastPro Mascara.

Prachi Desai: Prachi Desai (born 12 September 1988) is an Indian Bollywood film and television actress.  She started her television career as lead protagonist in the successful TV drama "Kasamh Se" on Zee TV.  She made her Bollywood debut in the 2008 film "Rock On!! ".  Her other notable features include "Once Upon a Time in Mumbaai" (2010), "Bol Bachchan" (2012) and "I, Me Aur Main" (2013).  She is also the endorser, spokesperson, brand ambassador and the face of Goa Tourism and Neutrogena products in India.  Desai is also a brand ambassador of Lux Lyra.

Milind Gunaji: Milind Gunaji (born 23 July 1961) is an Indian actor, model, television show host, and author, most known for his roles in Marathi and Hindi cinema.  He made his first film appearance in 1993's "Papeeha" and has since performed in over 60 films and acted as the host of the Zee Marathi channel travel show "Bhatkanti".  Gunaji has served as the Government of Maharashtra's brand ambassador for forest and wildlife.  Currently he is the brand ambassador for Hill Station Mahabaleshwar.

Specsavers: Specsavers Optical Group Ltd is a British optical retail chain, operating globally, which offers "optician services", along with eyeglasses, contact lenses and hearing aids.  In 2012 it had the largest single market share of the four major opticians, with 42% of the market within the United Kingdom.

Chain store: Chain store(s) or retail chain are retail outlets that share a brand and central management, and usually have standardized business methods and practices.  In retail, dining, and many service categories, chain businesses have come to dominate the market in many parts of the world.  A franchise retail establishment is one form of chain store.  In 2004, the world's largest retail chain, Wal-Mart, became the world's largest corporation based on gross sales.

Darren Kennedy: Darren Kennedy is an Irish television personality, IFTA nominated TV presenter, documentary maker, lifestyle writer and designer from Dublin, now based in London.  He is a contributing editor to the Irish Independent Weekend magazine.  He is a brand ambassador for the UK highstreet optician Specsavers.

Optical 88: Optical 88 () is one of the famous eyewear stores in Hong Kong.  It was established in 1984, as a member of of Companies, who owns largest professional optical retail network in Hong Kong.

Supporting paragraphs: Darren Kennedy Specsavers
Answer: Specsavers