Viewers do not want the BBC to change, the chairman of the BBC Trust will say as she calls for an "i-licence fee" to fund the corporation.
In a keynote speech at the autumn conference of the Voice of the Listener & Viewer (VLV), Rona Fairhead will outline the public's desire for "evolution, not revolution" for tomorrow's BBC.
BBC research, she will say, indicates the public's broad support for a universal form of public funding for the BBC - either through the licence fee or some form of household levy.
Ms Fairhead admitted that the BBC's agreement to take on funding of free licence fees for over-75s had followed a "very bad process" but decided not to oppose the change because the Trust had been told by the executive that it allowed them to have a "strong, sustainable" BBC.
Quitting would have been a "dereliction of duty" and she decided to stay there and "fight", Ms Fairhead told BBC Radio 4's Today programme.
"They (viewers) do not want fundamental change in what the BBC offers," she said. "They want it to be sustained, which is will be with this funding settlement, they want it to be strong, which it will be, and they want it to be protected much more in the future, which is what we are fighting for.
"That's not to say that there won't be changes. The BBC has to continue to evolve. It's just the nature of the beast. But is also needs to change in some particular areas."
The chairman is expected to state in the speech that the BBC "must not be treated like a government piggy bank to be raided when times are tough".
As the debate over charter renewal intensifies into the new year, the chairman will also argue for the views of licence fee payers to be taken into account.
The chairman will suggest six new public purposes to give those who pay for the BBC a better idea of what it exists to achieve.
The first three deal with the BBC's historic mission - to inform, educate and entertain.
The last three public purposes would be: reflecting, representing and serving everyone in the UK; reflecting the UK to the world and contributing to the UK's creative economy.