Ann: Half Year Report to Shareholders, page-80

I absolutely understand that.

In fact it is my precise understanding of all that which makes me ask why don't they just do that in the first case?

And, my auxiliary observation to that: Given they make a profit by performing the role of an intermediary in the supply chain, to the extent that they temporarily suspend acting as such an intermediary, that it has an adverse impact on profitability.
(You do know that, when you sell from inventory, you still have to account for the inventory you are liquidating. You know it doesn't come for free, even if it has been produced/procured in a prior financial period.)