This was discussed on Gerry Ryan's programme today on 2FM. Won't comment on what I thought of the guys that rang in first
The level of high level traffic over Dublin suggests that the North Atlantic tracks brought alot of the traffic in over the vicinity of Dublin VOR.
The traffic going North/South to form a cross would possibly be traffic from North Ire/Scotland/Manchester heading towards Tenerife/Lanzarote on the "Tango 9".
Depending on where the weather is out in the North Atlantic, the traffic from USA to Europe and VV can end up flying over any part of Ireland.
Some days up over Belfast the others down south over Cork.
Depends on the weather.
As one of the lads said a busy navigation aid like Strumble must have this sight over them most days.