This is what we found on Wikipedia regarding the The King's Singers:

The King's Singers are a British a cappella vocal ensemble founded in 1968. They are named after King's College in Cambridge, England, where the group was formed by six choral scholars. In the United Kingdom, their popularity peaked in the 1970s and early 1980s. Thereafter they began to reach a wider American audience, appearing frequently on The Tonight Show Starring Johnny Carson in the United States. In 1987, they were prominently featured as guests on the Emmy Award-winning ABC television special Julie Andrews: The Sound of Christmas.

Today the ensemble travels worldwide for its performances, appearing in around 125 concerts each year, mostly in Europe, the US and East Asia, having recently added the People's Republic of China to their list of touring territories. In recent years the group has had several UK appearances at the Royal Albert Hall Proms and concerts as part of the Three Choirs Festival and the City of London Festival. The King's Singers consist of two countertenors, a tenor, a bass and two baritones. Their latest album is titled "The Library Vol. 4", and was released in June 2022.