Already Have Mirror Holes? That's a Different Question
And yes, plenty of Austin Healeys already have holes where exterior mirrors have been fitted at some point. After several decades on the road, that should hardly come as a shock.
If your car already has a suitable mounting position from an existing or previous mirror installation, check what is there before choosing a replacement. There is little sense in pretending an existing hole does not exist.
The distinction is that the mirrors featured here do not require you to drill fresh mirror mounting holes simply to fit them.
For an owner with restored or undrilled bodywork, that can make the choice considerably easier. For a car that already has mirror holes, it means you can judge the existing arrangement on its own merits rather than creating yet another one.