The ones in the terminal apparently, but not necessarily the ones in the BA lounges, as I discovered last month while waiting for a delayed flight.

Was watching the screen for a gate assignment until the delay went long enough such that it disappeared entirely from the display!

Had to use the Heathrow website and refresh constantly until gate was assigned. Never reappeared on the monitor in the lounge. While walking over to the gate, I noticed the displays in the terminal with my flight, with status of Flight closing. Rushed over to the gate, which was mostly empty. Door closed about 5 min after I boarded.