I've said this elsewhere on FT, so will be brief.
Since the airline consolidation, most notably the UA/CO merger, TATL prices out of Houston have rocketed. When I last booked, in June for October, it was about $200 cheaper to fly LCH-LHR (via IAH) than it was to fly the same flights without the LCH-IAH leg.
Is this because LCH-???-IAH has effective competiton? (AA/BA via DFW vs UA via IAH) A few years ago, when you looked for IAH-LHR/LGW you had the choice of AA via ORD/MIA, UA via IAD/ORD, NW via DTW/MSP, DL via ATL/CVG and then BA or CO direct for a little extra. All those options have disappeared now.
The conspiracy theorist in me thinks that AA/DL may have just agreed to let UA "have" TATL from Houston so they only compete with the destination nation's Flag Carrier. The old Supply and Demand system raises the price.
In 10 years, the price has tripled, and what you get for the higher fares has decreased. And I will refrain from having my rant about changing the pmCO 772 on IAH-LHR to a pmUA 763.