Flight Radar is a hobbiest tool, it works on an entirely different method to airline/ airport timings. The quoted departure times are actually wheels up times, or as close as flight radar can get to those. Airlines work on push back times so at somewhere like Heathrow take at least 30 minutes prior to the flight radar time as the actual departure time.

If you do that then I’d say that BA267 departure times are remarkably good over the last 2 weeks, only 2 aircraft have experienced an actual delay to departure with neither long enough to accrue compensation. Additionally as CIHY states the oceanic tracks have been very south recently and the strong jet stream is adversely affecting westbound flights, in addition to the terrible Summer the U.K. is experiencing.