UK Air Fares

Hey, it's rip off time again folks !! Why is it because we are in the UK we have to pay so much more for a flight than than if the visitor pays for it in their own country? I was trying to price a one way ticket from Manila (Philippines) to London Heathrow. On the web I was quoted £1250 by a well known east asian airline for an economy ticket which is outrageous as it was not even a direct flight but involved a stop over. To rub salt in the wound, my visitor has obtained a seat on the same airline paid direct for it in Manila and it cost only £299. Not much difference is there !!! It's the same flight distance, same operator , same food I expect, same level of crew so why the difference? This sort of rip off really irks me... does it you ?