The question seems simple and the answer seems obvious. Yes, the UK government is accountable. If we understand being accountable as fitting one of the four types that Lord Sharman recommended, then it appears accountable.
- giving an explanation
- providing further information
- reviewing and, if necessary, revising
- granting redress or imposing sanctions
For the most part, this seems to be the way the UK government works. It justifies itself before Parliament and the people through a variety of methods and means. Parliament can hold it to account through select committees while citizens can use such things as judicial review. However, recent cases suggest a worrying trend to resist anything but superficial accountability.
The Crown will not explain itself when it kills its citizens.
The case is the drone strike that killed Reyaad Khan and Ruhul Amin who were both UK citizens. The drone strike was targeted at Khan. The PM justified the killing as self-defence. The UK, a nation state, had to defend itself against an individual, a citizen, by killing them with a drone strike. The UK also claimed that the strike was required to defend Iraq from ISIL. The citizen has no redress in this situation. They received no warning, no trial, and no appeal. The state decided to kill them without the constitutional recourse which is available in the United States.
When asked, the UK government refused to publish the legal advice that justified killing a UK citizen. If the government will not publish the reasoning or the legal advice that justifies the killing, can any citizen be safe? The highest duty within a state is justice. If the state cannot provide justice, can it consider itself legitimate? The state already holds vast power over the individual, including the power of life and death, so when it uses this power it must be accountable. If a government is unwilling to justify itself to its citizens, is there a difference between it and a gang of robbers? The UK government justified itself on “self-defence” without explaining why it delayed telling the public of the killing.
The UK government decided that a UK citizen was a threat to national security and killed them. The principle is that the Crown will kill people who threaten its security, the national security. In such a society, is political opposition possible? A few months later David Cameron said that the Labour party, was a “threat to national security”.
Does this mean that the government can kill them for the threat that they pose? Is it possible that Jeremy Corbyn can be killed by the Crown in self-defence? The UK took centuries to develop the practice of decent politics where political opposition to the Crown was not potentially punishable by death. Are we reverting to that earlier era?
No one is accountable, but we have learned lessons.
When a government does not account for killing its citizens, can the citizens expect justice? More to the point, can they expect someone to be accountable? It would appear not.
When Jean Charles de Menezes was killed, the state denied responsibility. They argued the killing was justified by the threat they faced. They claimed the Police Officers acted in self-defence against a potential suicide attacker. His family challenged the state’s claims. They brought their case to the highest court in Europe to which the UK is accountable. The judgement found there was not enough evidence to prosecute anyone for his death. He died because of the systemic errors, omissions, and missed opportunities but no individual was responsible for that outcome. The judgement means that like the 7/7 attack no one is responsible. If no one is responsible, but all parties involved were state organisations, then the state is responsible, but has it been held to account?
These two cases show the way in which the state can kill citizens and strangers without being accountable. In both cases, the state claimed self-defence. If self-defence justifies the act, does this explain enough to the public? Are the public, or the victims, able to hold the state to account. If the most you can expect is an apology, what does that do for the living? Are we to be grateful it is not us?
 Lord Sharman of Redlynch Holding to Account The Review of Audit and Accountability for Central Government (February 2001) p16 http://webarchive.nationalarchives.gov.uk/20081023163307/http:/www.hm-treasury.gov.uk/d/38.pdf Lord Sharman was quoting from Barbaris P (1998) ‘The New Public Management and a New Accountability‘ in Public Administration, Autumn. Also Neale A and Anders on B (2000) ‘Performance Reporting for Accountability Purposes – Lessons, Issues, Futures’ paper at International Public Management Workshop, Wellington, Ne w Zealand
 “So on this occasion we ourselves took action. Today I can inform the House that in an act of self-defence and after meticulous planning Reyaad Khan was killed in a precision air strike carried out on 21 August by an RAF remotely piloted aircraft while he was travelling in a vehicle in the area of Raqqah in Syria.
Mr Speaker, we took this action because there was no alternative. In this area, there is no government we can work with. We have no military on the ground to detain those preparing plots. And there was nothing to suggest that Reyaad Khan would ever leave Syria or desist from his desire to murder us at home. So we had no way of preventing his planned attacks on our country without taking direct action.” [emphasis added] https://www.gov.uk/government/speeches/syria-refugees-and-counter-terrorism-prime-ministers-statement
 Ibid “Barack Obama has since faced repeated questions about the constitutionality of such killings, with accusations that the US is engaged in extrajudicial assassinations.
The UK has no such constitution protecting individual citizens.”
 The attacks occurred on 21 August 2015 but the official notification was on 7 September 2015.
 Instead, it would appear when something does go wrong, we are told that lessons will be learned. Just as with the 7/7 attack when the government failed to protect its citizens, despite its extensive powers, it deflect accountability. http://news.bbc.co.uk/1/hi/uk/4763097.stm As the article notes, “The twin reports into the London bombings of 7 July 2005 are marked by the characteristically British habit in these types of inquiries of listing a long series of failures and then not blaming anyone.” It then quotes the Intelligence and Security Committee (ISC) report with the now classic Civil Service response: “We believe that lessons have been learned.”
 The Crown Prosecution Service (CPS) did find the Metropolitan Police Service (MPS) had breached the Health and Safety Regulations and were fined 175,000.
The family had settled a legal claim with the MPS out of court with the MPS paying them a sum just over 100,000 and their legal fees in return for the family dropping their suit. http://www.bbc.co.uk/news/uk-33066098