Seems to be being reported across the pond; confirmed as exLHR:
The plan is for daily service to begin Oct. 25, with a flight arriving in Las Vegas at 5:10 p.m. The return trip to London will depart at 7 p.m., Lampl said.
The airline will use a Boeing 777 configured with 274 seats, 24 of which will be “world traveler plus,” 36 business-class with seats that recline fully to 180 degrees and 214 economy class.
Fares will begin at $461 round trip, plus taxes and fuel surcharges, Lampl said. They should be available for booking by Monday on http://www.ba.com.
From LHR, this data would suggest a departure around 3pm and arrive back in to London around 1pm, probably not in time to use the Arrivals Lounge.