The earth's radius and the G variation

It has long been assumed that if the gravitational constant G was larger in the past, the earth's radius had to be smaller. The assertion holds provided the input from microphysics (in particular the equation of state) is independent of G. While this is true for some theories of gravity with variable G it is not so in the scale covariant theory, where the pressure can be affected by a variable G in a way that, for a constant mass of the earth, a larger G in the past implies a larger earth's radius. Comparison with recent palaeomagnetic data is presented.