The Chief Executive of the islands' Council has said there is "zero appetite" for Cornwall Council to take responsibility for the Isles of Scilly.
Speculation about a possible takeover has increased after the Authority delegated its finance and IT functions to Cornwall Council.
However, Theo Leijser said at the recent public meeting on St Mary's that decision-making will remain on the islands.
He said: "We are protecting that legally in the collaboration agreement and it is very, very clear what is and is not in scope. It is very clear... that the decision making remains in each respective authority."
Council chairman Ted Moulson said: "We as elected Members have made it very, very clear to the elected Members within Cornwall that this is a collaboration that is mutually beneficial and if at any time it [isn't] then we can move away from it."
Cllr Steve Sims added: "I think you'll find that Cornwall will be fighting hammer and tongs to keep us at arm's length, they don't want us. It would be a nightmare for them, why would they want to take us on with our particular challenges?"
"I can guarantee you, certainly at the moment, that there is zero appetite to even start thinking about it," Theo continued. "What the government is doing - don't forget we are a unitary authority - is encouraging districts and unitaries to come together as a larger authority... They cannot force [us] legally at the moment and I think the legal agenda will be so busy with Brexit over the next 30 or 40 years, I don't think they will have time to change the law."
"I and the rest of our colleagues fully endorse that," said Cllr Moulson.
Cllr Sims said: "We cannot afford the level of specialisation we need in the 21st century unless we collaborate", to which Theo added: "But cleverly, and we are protecting ourselves."