In that the Hounslow Loop is within the London zoning area, then all travel costs should be exactly the same from zone to zone as they are on the Underground, or for that matter on the Overground, using an Oystercard. It is only once you go past Feltham that you leave the zoning area, and that is well after the end of the Hounslow Loop.There are some anomalies - when Southern were on strike and I had to go to Victoria via Vauxhall and the Victoria Line rather than my usual route from Clapham Junction, I was surprised to find that I was charged more to reach Victoria underground station by that route than to Victoria mainline by my normal route - but mostly the zonal fares should be consistent, so anyone hoping that nationalising SWR would bring down fares on the Hounslow Loop is likely to be disappointed.
Richard Greenhough ● 207d