What you're forgetting is that since 2007 both NCL-STN and NCL-LGW have been cancelled. 2016 NCL-LON figures are just over half what they were back in 2007.
2007: 902,784
NCL-LHR 495,366
NCL-LGW 109,649
NCL-STN 297,769
2016: 497,386
NCL-LHR 497,386
407,418 passengers used NCL-LGW and NCL-STN in 2007, all of whom were point-to-point customers. Meanwhile, BA carried 495,366 passengers, some of whom were connecting passengers. The figures show that LGW and STN passengers are now flying to LHR (or not at all), and that many connecting passengers are using alternative airlines to BA. The figures strongly suggest that BA carried a lot fewer connecting passengers in 2016 than they did back in 2007, meaning Emirates (and KLM etc) have had a pretty major effect.