The problem with ex UK flights at the moment (at least during peak travel times) is that European airspace is so full, that flights that are ready to depart are held at the gate for considerable time before getting permission to depart. I was on EK16 ex LGW two days ago. Flight was ready to go at the correct time (14:30). Doors were closed, airbridges retracted etc. Captain told us that we had a 45 minute wait until our takeoff slot. It would appear that EK takes this into consideration when setting the block time because the flight time was normal and we landed just 10 mins behind schedule. Looking back at FR24, you see this happen very regularly.
EK31 (ex LHR) that same day was not so lucky and passengers on what is normally a doable 1h05m connection had to be rebooked. As Will08 also mentions above, this is standard ops for the airline, but inconvenient for the affected passengers (especially those with no lounge access now having to sit for hours in the terminal)