flightcatcher rudestuff Thank you so much for your answers, they are very helpful
That of course explains why a Prague flight to London (City or LHR) usually comes in straight down from the east, as previaling winds in London are more usually from the West. I sort of suspected that, but did not quite appreciate why. Got it now!
Edit..on reflection..another dumb question. I now understand well why a plane wants to land into the wind. But how does taking off into the wind assist it?