Maybe they are going to get US immigration staff to work mornings and evening with a long sieasta in between like the Spanish do.
The retiming makes BA1 a little risky given the LCY fog at certain times of the year. There is no time to relocate the plane for STN/LGW back to LCY.
Didnt the original BA001 flight take off around around 9:50 am from LHR as well?