Summers criticized what he took to be Gilliinson's bias toward London orchestras and took Gillinson to task for portraying orchestras as "a bunch of complainers."
"Why is the pursuit of excellence any less serious in, say, Birmingham, Gateshead, and Manchester than in London?" Summers wrote.
The Hall_, Britain's longest-established symphony orchestra, is located in Manchester.
"Clive Gillinson's real complaint seems to me to be that the Arts Council doesn't give the LSO substantially more money than any other orchestra in London," Summers said, "thus allowing them to preserve and build on the competitive advantage that they have developed partly as a result of having, historically, higher ACE funding."
Gillinson claims that he said no such thing, and that his comments at a conference of the Association of British Orchestras were made in reference to the U.K.'s Arts Council's policy of judging all orchestras on the same merits.
"What is very clear is that U.K. orchestras vary greatly in the scale, scope, and quality of what they do," he wrote, "as do organizations in all art forms. It is the job of the Arts Council to have very clearly defined criteria for public funding of the arts, and to have the expertise to make funding decisions based on these."
In a previous Guardian article, Gillinson noted that as an advisor to the Arts Council as well as the head of an organization receiving funds from the council, Summers' statements could be read as both defensive and a conflict of interest.
Gillinson will leave the LSO this summer to become the director of Carnegie Hall in New York.