Hi DeA320, Aer Arann had an order for 10 x ATR 72-500, they received 5 of them, EI-REL, REM, REN, REO and REP. If I recall they sold REN to a Swedish Airline, Goldenair (?) as they had been leasing that plane to them for some time. I think they also sold EI-RER before it had actually been delivered, again to Goldenair.
That leaves the 4 listed on Jethros to be delivered, have't read anything to suggest that they won't be coming, but since they did the reduction in fleet nos/growth plans maybe they've deferred. Although I don't work in the industry I follow pretty closely, always thought they should have got 5 x 72-500 and 5 x 42-500 to have a brand new fleet. I wonder if they could uprate the remaining order backlog to the new 600 variant, may be ideal for LCY ops as uprated engines...
anyway, rather than rambling on, i hope that helps.