Looking at dual airport operations (EK, QR, TK, SQ, CA - though I am sure there are more), the yields out of LHR are higher than out of LGW. And in some cases the magnitude is 50% or higher. All premiums ex-LHR are high double digit yields ahead of LGW. The weakest is CA (though there is still an LHR premium), which is a bit of discounter in whatever market it operates to in Europe.