[Geezer (OP)]

If I even dare to touch a piece of Cheddar and stick it back in the fridge, it does not take long before it turns into something Quatermass (O.B.E.) would have been proud of.

I can pretty much do anything with a nice piece of Stilton, Gorgonzola, or Danish Blue, and bugger all nothing much seems to happen.

Why's that then?

[RD]

Maybe a pH thing: stilton is more acidic than cheddar.

[ acid inhibits mould growth, e.g. vinegar ]