Loaning out a gold-backed currency isn't loaning out gold. You seem to be confusing "1 pound of gold" with "a piece of paper saying that bank X will trade this

Loaning out a gold-backed currency isn't loaning out gold. You seem to be confusing "1 pound of gold" with "a piece of paper saying that bank X will trade this for 1 pound of gold". The two are not the same.