While there is a fairly good account of the introduction of the expression OK into the UK in the song “Walking in the Zoo” sung by Alfred Vance, the Great Vance, one of the great “lions comiques”, it probably emerged from the Greek migrant population in Boston or New York and is first recorded in use in 1839.
The sheet music here is decorated with a drawing by Richard Childs and dates from 1871.
Sakis Rouvas (whose birthday is tomorrow) popularised the term “Ola Kala” in a Greek pop song written by the American songwriter, Desmond Child in 2002. Child also wrote “she bangs” and “La vida Lorca” for Ricky Martin.
animate-tim.com 
and I thought “OK” was english!