G-YMMT did indeed operate today's BA10 (and therefore yesterday's BA9 as well), but generally BA10 isn't scheduled to land until 1825. (It's actually slightly ahead of schedule).

Therefore something must have happened to the aircraft that was planned to operate it.

As BA9 is scheduled for 1605, it's likely to be quite a long delay if YMMT is in fact used - probably closer to four hours than two, possibly even more.