Global wine shortage

[Fred]

Why is supply dropping whilst demand grows?

The ones making the wine have found out it tastes nice, got into a drunken stupor and forgot you need to make more for next year.

And does this means I'll have to order Madames boxes of vin plonk in advance to avoid disappointment?

No it's just a ploy to get you to buy all those 10lt box's that didn't shift through the summer.