Wondering if anyone can advise

I have just reserved seats for an upcoming flight to Calgary, The aircraft in use is a 787-9 and I have been allocated seats 1a & 2a for myself and wife.

I assumed from seat maps that these seats on the BA 787-9 aircraft are in the first class section. I have spoken to the Silver Exec club and they have advised this is correct, but they are using it for business passengers on this flight!

Does this sound correct or am I likely to turn up at LHR to find they have moved me back to the business section?