USD-GBP boasts of its identity as the most crucial, unpredictable and exceptionally volatile currency pair in the world trading marketplace. The main driving force behind their volatility can be mentioned as the correlation they share which is contradictory in nature and the combined effect they have on the other significantly influential currencies, as well.
As the proportionate change, between them is worth consideration it would cause notable impact. The main factor, however, is considered as the Interest rates and the Monetary Policies of the Federal Reserve Bank and the Bank of England. Policy Decisions and the Interest Rates contribute to the growth rate of the currencies.
It is hence a natural assumption that important decisions in the International Market are taken considering the Currency Proportion and the Correlation in the current scenario. It is certainly not the case that Federal Reserve Bank and Bank of England are the sole, dominant factors as the movers of their respective currencies.
By taking account all the vital factors, it can be easily concluded that the BOE and FBI policies and the decisions defines the Economic Phenomenon being the sources of impetus for the movement in the GBP and USD.