Capital gain / loss by exchange rate

I have bought and sold US stocks. To my understanding, the cost and the selling price have to be converted to sterling pound in order to calculate the capital gain. Suppose the gain is USD 100, as different exchange rates are used in converting the cost and selling price, there is a loss of GBP 50 after the conversion. How to report this in the tax form in this case?

Hi,
As both the purchase and disposal price need to be in sterling then it would be reported in the same way it is just that you have made a loss rather than a gain.
Thank you.