Like any commodity, the price of gold is somewhat dependent on supply and demand.
A few years ago, our then chancellor (G. Brown), announced that the UK would be selling a sizable chunk of its gold reserves, (some of the money raised would no doubt go toward the profligate spending of our government).
This announcement had the obvious effect of depressing the market price of gold, since supply was now known to exceed demand (at least in the short term).
By making this announcement, the UK lost a significant amount on this pre-announced sale � all due to our brilliant chancellor, now Primeminister.