British governments should protest violations of human rights wherever they occur.
Whilst I do not dispute the fact that we, the British, are the finest race on Earth and more than capable of showing everyone else how they could treat their citizens (or, rather, this was the case until a decade ago), it is not the government's place to "protest violations of human rights wherever they occur."
There are a couple of strands to the argument, but they come back to libertarian thought. Under this philosophy, the initiation of force against a party—whether by government or private agents—is strictly prohibited. So we could not actually force any foreign government to enforce human rights.
And this makes any protestations about the treatment of any government's citizens empty and hollow; it diminishes our country's clout by threatening what we cannot—or, rather, should not—enforce. We look stupid or ineffectual: both options diminish our ability to do anything effective.
The only way in which we can interfere in another sovereign state's policy is if we are invited to defend those who are being atacked. The philosophy being that we may not initiate force, but those who are being atacked may ask others for help in defending their property.
It sounds weird that a libertarian should defend isolation in a country, but my reading of it allows for nothing else. If we protest about innocence of prisoners, we have to be able to back it up and, especially now, we cannot do so with military action. We could try to enforce good behaviour with trade blockades except that we do not control our own trade policy, so we cannot.
Our only option is either to shut the fuck up, or to sit and protest and hope that the offending countries do not realise how utterly ineffective we are.