mjenkinsblackdog, the QRH says NEAREST SUITABLE AIRPORT. There is no mention of below, ahead, behind or to either side.
If you were an experienced jet pilot you wouldn't be stirring the cr@p here. You wouldn't question a crews decision to carry on to DUB if they had an engine failure overhead MAN whilst in the cruise. The ONLY time a crew would drop down from overhead in the cruise to an airport directly below is if there were NO OTHER SUITABLE airport within 100nm. It looks like you are just trying to stir the pot because you would know that there are plenty of suitable airports within gliding distance from overhead MAN.
A jet cruising at or above FL310 and experiencing an engine shutdown would need at least 100nm to lose the altitide whether it was in a straight line to an airport ahead, behind or underneath. An engine shutdown is not a mayday situation unless there are additional problems such as a fire or anything that is immediately endangering lives. A mayday may be called initially but once an engine has been shut down and provided there is no fire, severe damage or separation then the nature of the emergency can be downgraded to a PAN which will still provide priority handling by ATC.
So, a B737 suffering an engine failure overhead MAN en route to DUB would require several minutes to identify the problem, perform the recall drills, perform the QRH checklist whilst handling any driftdown if necessary due to weight. Considering the distance from MAN to DUB is approximately 130nm and also considering that the a/c still has an operating engine and is perfectly capable of flying on that single engine and considering that the operator has a maintenance base there and considering that the original destination was DUB anyway, all considered in that order, by the time a decision is made the a/c would have been requesting descent for DUB anyway!
So mjenkinsblackdog, unless you are really an experienced jet pilot leave the decisions to the real pilots who were there and are trained to make those decisions in the first place. I wouldn't advise making those kind of cut and dried statements with such authority if you are being considered for a command.