A few points to inform the debate (have to admit cannot confirm their veracity but have spoken to some who should be in the know).
I believe one colonel failed to attend because he is currently on remand waiting to go before the beak for an alleged murder. The second chap did turn up at his unit lines, but just to dump his kit off and hand in a letter of resignation.
The General Medical Council is a very powerful professional body, perhaps the most powerful in the country after the Bar Association. It almost certainly will not take disciplinary action against these men (at least the one NOT accused of murder), indeed it will probably support them. Certainly the British Medical Association (the doctors trade union) will back them in their decision not to soldier on. The NHS trusts that they work for will just be happy that they dont have to cancel operating lists and fail to meet their targets. The GMC and medical Royal Colleges consistently refuse to compromise on any of their rules to help the forces out in operational situations. The DMS and the armed forces as a whole simply have no clout with them, we are too small and unimportant in the bigger scheme of things. Finally, the DPP and the Army prosecuting authority know that they will lose this one at the European Court of Human Rights, certainly even before that in the UK courts. These two geezers know this.
The NHS is a more important organisation than the armed forces in the view of most of the great British public. The average citizen, whilst perhaps believing these guys should get a slap on the wrist, would be outraged if they were given any form of custodial sentence, which meant they were not available to treat patients in their local hospital. For politicians, there are more votes in the NHS and what it does than there are in the armed forces and what we do. Yes, when the shooting starts we will go up the political agenda a little (note the pay rise of the armed forces compared to the nurses and teachers) but that will soon be forgotten about and we will return to being that well known bunch of right wing, foul-mouthed, recruit bullying, larger louts.
Finally a note on pay for these guys two guys. Medical officers who volunteer for service are only paid the same salary as their equivalent Regular Army rank. Those subject to compulsory call-out can receive compensation for lost earnings (both NHS and private) up to the figure of £150,000 per year.