I'm still curious about the logic behind moving into MAD. I can see the appeal of low-cost terminals at MRS, GVA, LYS etc, but MAD is one of Europe's largest airports - not just in terms of pax numbers, but also in terms of airfield size.
MOL has regularly pointed out how little he likes MAN compared to LPL - not just because of charges, but also because of the congestion around the aprons.
FR like small airports, but they also like high yields and good deals. Eventually, as they grow, they have to start more operations from busier airports - as much due to the impact of the traffic they generate themselves. Looking at the USA, Southwwest have a major presence at large airfields like LAS, PHX, etc.
Presumably, the opportunity to get into MAD, which is a huge market with relatively few loco flights, was just too good to miss?