M is not the head of Mi6, only the 00 section. I have doubts and misgivings that Bond even works for MI6 in the Flemings books as claimed by some fanboys, but they refuse to listen to reason. It has been branded by the producers that Bond works for Mi6 in the movies starting with Brosnan Bond.
Yes. I was just merely stating that having Liam Neeson be a hypothetical 'M' in a future Bond movie would be a slap in the face to all of MI6 (including the 00 sec.) specifically because of his Irish roots, given the ugly past between British intelligence and the IRA.