JN - you're right that the precedent isn't direct, but the point I was making is that the initial bleating we were hearing suggesting that senior officers never, never, ever get involved in politics and that this is some sort of disgrace without the slightest parallel was somewhat off-beam (I would slightly dispute your portrayal of Kitchener, but that's a matter of interpretation).
I agree, though - the problem Sir Richard faces is that if he is to accept the offer which appears to have been put to him, his motives for criticising the government's policy will undoubtedly be put down to personal ambition, rather than genuiune concern for the troops in a series of off-the record briefings from the usual spin-meisters in London.
Had he waited for some time before accepting this offer, then things might be different, but he is now in serious danger of having his term as CGS being portrayed less favourably than he deserves.
Not so much an own goal at the moment and more a case of some sloppy tactical thinking in front of goal which might lead to an unfortunate outcome.