People can keep money or invest in other channels such as stock, real estate. While fiat money is strongly affected by inflation, stock is too risky and real estate faces the risk of housing bubble or redistribution after war. Gold, a limited and precious material, proves its value every time, esp in crisis.
Thanks to their colonial past, the British, despite being such a tiny island nation, hold a disproportionate amount of assets. If the British think that gold is valuable, every one else should think so too. After all, they ruled almost all the world at one point, so they must know something we don't. People should definitely buy gold.
I think that having a stash of gold is a great idea for any country, so Great Britain has the right idea. Gold is one of the few things that will not lose its value long-term. The citizens of Great Britain have some protection since their country has so much wealth in reserve, and individuals can protect themselves and their finances by doing the same thing.
The holding of gold as a hedge has a long history in the financial markets. Gold value typically increases during times of war or economic crisis. There are many ways to acquire gold holding such as gold stocks as well as gold bars. The future is always uncertain and having gold is another way to diversify and reduce the risk of investing.
There are no longer aspects of the world's economies that can be considered a "sure thing" but, history has shown that the most apparent staple is precious metals, with gold being the most stable. In the event that currencies fail or become useless, gold would appear to be the best chance of a surviving monetary standard, though certainly not guaranteed.