Great report! I've been upgraded once to business class on CX but it was a short flight from SIN to HKG.
Love your pics and the food looks great.
It's quite unusual to be able to land quickly at LHR which is known to have a long stacking queue, last week when I picked up my parents from LHR I saw their plane stack for 4 or 5 times before being able to land!
You mentioned using a Seat Alert app in your post, which one is it? Is it this one: Seat Alerts by ExpertFlyer ?