LHR T2 has similar automated passport barriers to BRS, and my passport couldn't be read by those gates recently. A Border Force officer at LHR confirmed that my passport is OK, but that there's a problem with their gates. I'm assuming it's either the location of the RFID antenna on the gate, or a bug in the software that can't open/validate the data from the RFID. I can't establish if there was a change in the manufacturing process (either physical location of the RFID/Antenna or the way the digital signature is applied) that would account for the problems. (I'm also assuming it's the RFID, not the machine legible part of the passport).
I've heard nothing from the aiport about my question / complaint to them about it.