Money is worth whatever society deems it is worth.
Humans have no inherent concept of the worth of money.
That is why one currency can be worth a lot, while another can be pretty much worthless.
Some time ago, GBP could afford you X things... now, it can afford you less than X things.
For now, this change in worth of GBP is purely speculative, but it may become real.
The speculation is that, with the potential exit from the EU, products from the UK will find it more difficult to compete with products from the EU. Less international sales of British products, leads to less willingness to purchase GBP in order to purchase those British products.
Supply and demand then factor in... less demand for GBP, for the same supply, leads to lower value of GBP. Yes, in these currency markets, value is attributed to the currency, in spite of what it can afford you in reality.
Add to that the fact that the Bank of England has announced that it would inject a considerable amount of GBP in the economy, to try and keep it flowing, and you see supply increasing, thus diminishing further the value of GBP.
Of course, this value of GBP is only relative to the rest of the world's currencies. GBP's worth in British products should remain similar, although it should factor in the requirement of purchases from other countries in order to manufacture those products.
You've heard of the problem that no single person on Earth can build a pencil, right? Lots of products require elements from other places, which are now relatively more expensive, thus leading to an increase in the price of British products to the British people, using GBP.
These effects can snowball, but will usually tend to an equilibrium for the currency in question.
Simultaneously, the world goes on. Other events unfurl and affect this or that currency. It is a dynamic system, with some checks and balances put in place by the governments, the banks, the insurance companies, or whatever...
Most "Liberals" would let the market sort itself out, with no checks and balances... methinks that would be a bad idea, but I know not enough to really form an informed opinion. (Am I showing my bias due to my background in a socialist country? [actually socialist, not communist disguised as socialist like the USSR])
(PS: this is all BS I just made up!)
