You can also do an airside transfer at MUC T1. Transfer times are very short, even if going landside, since T1 Modul B where BA flies from is generally quiet. There is now even a security fast track line for the odd busy occasion, although this is an unpoliced entrance leading to the front of the general security queue, giving you the feeling you're pushing in and resulting in a chorus of tut tutting by those you're pushing in front of.