The 777 to AGP was due to 737 issues.
The NCE and BCN on 0/10 were due to the French ATC strike.
The FCO on 18/10 was due to the Italian ATC strike and I think it was NLM. The 767 from the FCO was then redeployed on an MXP run to help with extra capacity to Milan.
I'd think it's pretty straightforward what BA will do in similar circumstances in the future. The 787 will provide extra capacity where required. The 777s and in particular, the 777-3s still have a number of years left in them so again, they will be around to cover. Don't forget that the 777-3 has more seats than most of the high-J 747s.
Good to keep track of these subs. Also think it is to BA's credit that they are resourceful, where possible, during irrops.