There's always the UK and Ireland list of timber yards on this forum.
If you scroll down to the Duffield entry and then scroll right to the notes link, you'll find a very interesting write-up of how the yard is set up.
Your example is not the situation that I was describing. If Rod had been invoiced for the goods, and paid the invoice, he would have good title irrespective of whether his supplier had paid for the goods.
As Rod only took delivery of the goods, he was not a party to the sale and...