You don't need to be anonymous. Legal tender Gold coinage in the UK is free of capital gains tax, so even if the spot price goes up 1000% you still pay nothing to the tax man on sale.

For this reason alone lots of the extremely wealthy hold it as a hedge.

At volume the premium over spot is about ~6% even straight from the Royal Mint

Example: https://www.royalmint.com/invest/bullion/bullion-coins/gold-...