Virgin Atlantic and American Airlines both have one stop tickets from LAX to London around $587 to $600 round trip for July 2018 departures.
Both tickets route through Las Vegas. Virgin Atlantic and British Airways fly Las Vegas to London Gatwick nonstop flights.
Virgin Atlantic at $587 uses a Delta LAX-LAS flight connection and $600 AA ticket uses AA LAX-LAS flights.
Virgin Atlantic LAX – Las Vegas LAS – London Gatwick LGW – LAS – LAX
American Airlines LAX – Las Vegas LAS – London Gatwick LGW – LAS – LAX
Summer 2018 is an exceptional year for unprecedented low summer fares to Europe. Over the past three years there were brief opportunities for a day or two during the spring months to book tickets in the $500s from California airports to Europe in July. So far this year, this have been fares in the $500s for July departures from LAX, SFO and SJC to many different European airports for several weeks over the past ten weeks.
London, Paris, Copenhagen, Rome are some of the cities that have seen discount summer fares for July departures.
Sun Mar 4 – July fare San Jose to Paris $573 SkyTeam
Sat Mar 3 – Oneworld LAX to Rome $499 July-Aug 2018