Professor Tom Devine, professor of history Edinburgh University, said Gray's language and opinion, expressed in an essay published last week, was "disgraceful" and not an apt description of the English population in Scotland or its contribution to Scottish society.
Gray, author of Lanark, has said he is not anti-English but that he was describing how although some English settle in Scotland and are "as much a part of Scotland as Asian restaurateurs", colonists "look forward to a future back in England through promotion or by retirement".
Gray, who made the comments in an essay in a book called Unstated: Writers on Scottish Independence, said the ensuing row had left him mystified.
However Mr Devine said that not only was the language inappropriate, but ignored the contributions made to Scottish culture by the English, as well as ignoring the contribution made to the British Empire, and its own history of colonialism, by Scots.
Mr Devine said the last census showed there were 420,000 first generation English in Scotland.
He added: "I think [Mr Gray shows] a disgraceful attitude. We have got to remember that the current Scottish population is so vibrant because of the English factor."
Mr Gray's comments were reported the day before The Herald published an interview with the departing artistic director of the National Theatre of Scotland, Vicky Featherstone, who said a period of anti-English "bullying" – criticial comments which focused on her Englishness – had led to a brief crisis in her tenure.