RE:Add Ascot to the failure pile like Pure Gold...Of course narrow vein mining is risky. The risk is not employing topdog airleggers. As a topdog airlegger told me, he worried more about the the other miners competence than rockfalls.
The other risk is grade and continuity , hard to establish. You mine for grade and drill for structure.
Risk goes both ways and in Wesy Oz where in am from there have been incredible success stories from narrow vein mines due to the bonanza cash flow they can produce