GBPJPY View!!FX volatility is a key, yet unknown parameter of an FX option premium, so dealers use implied volatility as a stand in. If actual volatility matches implied volatility over the life of that option it should cover the premium, with the disparity potential making FX volatility a tradable asset. Implied volatility therefore represents the expected realised volatility and should demand additional premium if its expiry includes a high volatility risk event, such as an election.
Historic volatility is actual/realised volatility over a particular time frame in the past and can provide a fair value measure upon which to gauge implied volatility.