Fleet departures.

4 more aircraft have recently been withdrawn from service and stripped of titles.

EI-DHI (Stored at Norwich)
EI-DHJ (Stored at Norwich)
EI-DHK (Stored at Prestwick)
EI-DHM (Stored at Prestwick)

Why they have withdrawn these 4 is a total mystery to me, as there are many more older aircraft in the fleet. (The likes of the EI-DA* and EI-DC* series)

Maybe someone else could shed some light on this.

Regards

EI-DCL.

EI-DHI was on lease from RBS Aviation Capital. RBS likely financed the order for the production of EI-DHI.
The rest of the aircraft you mentioned would have been similarly leased, as you had mentioned earlier, ryanair would not sell it's more newer airframe as opposed to it's earliest airframe. Well EI-DAC as you will see later is ryanair owned. (Flew on her 3 weeks ago, budapest based).

Ryanair since the 737-800 have never purchased second hand aircraft, however aircraft are either purchased through ryanair's own pocket (loan or no loan) or the money is financed through RBS/Hong Kong Aviation and the aircraft goes on lease until the end of the agreement. The agreement could be that once the aircraft has reached a certain number of flying hours, it must be returned to the lesser. Or maybe the aircraft was on lease until it has reached the loan amount and the aircraft becomes the property of ryanair. Either way it looks as though the lease agreement had expired or maybe ryanair terminated it earlier. Who knows?

http://www.planespotters.net/Airline/Ryanair

As you can see from the link above, most of ryanair's fleet are company owned. The number of aircraft in the fleet will likely remain stable until those on lease are returned. As you may or may not know, ryanair have not yet placed any new aircraft orders, and until this is sorted out the fleet will likely shrink slightly in size. If ryanair continues to show a monthly/quarterly/yearly improvement in profit and passenger load (see recent news) then ryanair will most likely place new aircraft orders to respond to the growth and domination in the low cost airlines market.

And the moment, ryanair's reason for not placing any further aircraft orders is due to boeing not offering them any considerable discount. The airline will likely jump in for orders when large orders from other airlines are lost (Norwegian air). And that's when boeing willl be forced to negotiate with ryanair in order to keep the workers at the 737 factory in employment.