I was on the same flight, I have to say you were keeping track of the turns a lot better than I was.
I have it on the authority of one of the American enthusiasts (who had come from Dhaka, and had links to Ian Allan tours) that we were in military airspace out to the west (Welsh border somewhere). They had supposedly opened it to allow the chase plane to take photographs.
Not sure on the truth in this, but it fits with what was said in the Birmingham thread on Thursday:
http://www.pprune.org/airlines-airpo...ml#post8330475