Thanks Oaxaca, I'm going through T4 in MAD this weekend with a 45 min connection from LHR inbound (IB metal) to onward Spanish domestic flight - presume T4/T4 is much easier than T4/T4S?
I'm on same ticket/booking so not overly concerned if problems (IB can put me up overnight and early first flight to BCN doesn't lose me much time 'on the ground')