Ahh I am out of date on my data. When I last used LHR-SNN the aircraft over nighted at LHR, and even after the re-introduction, the first SNN-LHR was due to arrive after 11am. What is clearly sub optimal is that the first wave for this aeroplane every day is at 08:45, meaning it's impossible to get into London for an early meeting without night stopping in the capital. That's why the early short hauls into LHR are often packed.
In this case the first LHR-SNN gets you in for early afternoon !!
Jack1985 I think the point is it would be even busier if it was able to get into LHR earlier but EI have shown they prefer to use those slots between DUB and BHD.