Craig Murray, the former UK ambassador to Uzbekistan, apparently faced a similar situation to Salmond.
" I too was accused of hideous offences under a civil service disciplinary code and barred from taking any action to defend myself. I was not allowed to speak to anybody at all about the charges, and particularly not allowed to know the identity of my accusers, or to organise witnesses in my defence – which appears the exact procedure which Alex Salmond now, with absolute justice, complains of. These Civil Service disciplinary investigations are contrary to all rules of natural justice, and designed to facilitate executive stitch-ups, not to uncover the truth....
...The charges against me were entirely fake and entirely vexatious, even malicious, issued after I had objected to British complicity in torture in the “War on Terror”, which the government denied at the time, calling me a liar, though now admits. The charges were designed to destroy my reputation. "
https://www.craigmurray.org.uk/archives/2018/08/when-they-decide-to-get-you/Murray says the government leaked the charges to the Daily Mail to ruin his reputation and he suffered a mental breakdown at not being allowed to defend himself. He said he repeatedly asked the Foreign Office to refer the matter to the police so he could get a fairer investigation, but the FCO refused. Eventually he was cleared.