Re : 9min to mach 2.
Not sure you can get CG back that quickly.
In the (restored) Sim with a lightweight fuel load that will not get you anywhere and not bothering about the CG, the absolute minimum time to Mach 2 at 50,000ft on a pretty constant VMO chase is just over 15mins, so really unlikely that this was possible in real life....but will stand corrected if someone says other wise.
The A/C had diverted to cardiff as they had suffered a engine surge due to a double intake lane failure and had to slow to subsonic early. That coupled with additional time with engines running at JFK meant they were just not comfortable about coming to London and possibly declaring a fuel emergency.