Some time before the idea of a black hole was conceived, a physicist named John Michell was thinking about the escape velocity of stars. He realized that as the mass of the star increased its escape velocity would eventually reach and then exceed the speed of light.
For obvious reasons he coined the term "dark star" for such objects. Other physicists honored his work by calling them "Michell Stars". They have no event horizon in the GR sense. And the laws of physics inside them are the same as the laws of physics here on Earth. Gravitons obviously escape from them, and a vehicle that could use gravitons for propulsion also should be able to escape.
Perhaps Dr Hawking is on to something?
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BTW, John Michell also invented the torsion balance used by Cavendish to make the first laboratory measurement of the universal gravitational constant.
