MAN is still just over 2m ahead as it surpassed the 27m pax mark in June.
Overall, the MAN growth rate has been higher than STN so is expected to be at 28.9m by the time STN reaches 26.5m.
Where STN may eventually take the lead is when the MANtp works really take hold. It means a constrained site at MAN and thus limits growth. But then for a single terminal airport with no plans for major expansion yet (new arrivals hall aside), that probably limits STN somewhat too.