New £7.4k gold loan - "up front payment"

Interesting point. We get a trading gain from our money. Could it be capital gain in that case?
Certainly not an invitation to trade.
Would purchasing a 2 part contract, one for supply and another at a later date for a higher payment for the borrower to repay the lender, produce interest or capital gain?

I am open to learning how risk sharing impacts on taxation.