The British political system has been decaying for decades. The main parties are split into hostile factions. They play games with our fragile constitution clumsily, like children playing with boxes of matches. The American diplomat Dean Acheson once observed that Britain had lost an empire but not yet found a place in the world. That remains true. Britain is only half in Europe, a semi-detached member punching below its weight and size. Foreign invasions, terrorism and mass migration have bred fear and insecurity, conditions easily exploited by extremists.
Our increasingly disunited kingdom is threatened by powerful forces of nationalism - pressure exerted by those who would quit the European Union or the United Kingdom or both, and from those who would impose their values and beliefs on the rest of us. That threatens our secular tradition. There is a risk that our governors may sleepwalk into leaving the European Union, and that Scotland may leave the rest of the UK, and that Northern Ireland will remain politically polarised.
Disintegration and disengagement would weaken our capacity to tackle the problems that cannot be solved by a single country - perplexing problems of corruption, inequality between rich and poor, racism, xenophobia, the misuse of religion as a weapon of mass destruction and the devastation of our eco-system.
The Astronomer Royal, Martin Rees, has warned that we are "destroying the book of life before we have read it". The pressures of a growing human population and economy, on land and on water, are already high and we have a responsibility 'to our children, to the poorest, to steward the diversity and richness of life on earth'. Working across Europe and beyond it, we must also tackle world hunger, disease and over-population; the effects of wars that have destroyed stable societies and resulted in millions of refugees; terrorism, racism and political extremism.
This is the worrisome context in which my book explores the five ideas I have chosen to fight for - human rights, equality, free speech, privacy and the rule of law. They reflect my practical experience and personal choices.
In 1968, Harold Wilson's Labour government rushed an emergency bill through Parliament in three days and nights. It took away the right of British Asians from East Africa to enter and live in the UK. It was racist, in breach of a pledge by a previous British government - that if East Africa's newly independent governments expelled British Asians', they would retain the right to settle in the UK. But because the Westminster Parliament is supreme and the courts cannot strike down Acts of Parliament, the only way of challenging the law was to complain to the European Commission of Human Rights in Strasbourg. That seemed to me to be absurd.
I tried to persuade our judges to take human rights more seriously, quoting American and European analogies. My successes were few. I was able to achieve more in two years as special adviser to Roy Jenkins at the Home Office - in 1974-76 - than in ten years at the Bar. We shaped sex and race discrimination laws and advanced the case for a British Bill of Rights.
Back at the Bar I developed a practice in what is now known as public law - the judicial review of the actions of public bodies to ensure they act lawfully, rationally and fairly. I argued before a new generation of judges whose values were very different from their predecessors. There were clear limits to what could be achieved using the judicial process. In 1993 I became a Liberal Democrat peer focussing on constitutional and human rights issues.
Peers are unelected and independent-minded - counter-majoritarian and sometimes in the vanguard of ground-breaking reform. About a fifth of the House of Lords are not appointed by the political parties and sit on the cross-benches. That secures our independence. Because of them, the government does not have a commanding majority and can be defeated by cross-party alliances. We have much more time than members of the Commons to debate and introduce reforming Bills. And among the politicians of yesteryear are experts in many fields, including law and government. It is a community that includes many women, those from ethnic and religious minorities, the professions and universities.
For all but the five years of coalition government, I have sat on the opposition benches under Conservative and Labour governments, working with colleagues from all parties and none, as well as civil society. I used public lectures and questions to Ministers and private member's bills to achieve reforms - bills on human rights, equality, civil partnership, forced marriage, constitutional reform and defamation.
Liberal Democrats suffered a devastating defeat in the 2015 Election, but I do not believe that the British people meant to reject liberalism. The current government wants to suppress extremist activity, and the Prime Minister and Home Secretary define extremism as 'vocal or active opposition to fundamental British values'. Those surely are the values of a liberal society that include freedom for political dissent and respect for human rights and the rule of law.
Those values are threatened not only by terrorists but the State and its agents and populist politicians. Human rights are under threat at home and abroad. So is the international reputation of the UK as a country that respects the European rule of law. David Cameron's government was elected with a pledge to tear up the Human Rights Act, replacing it with a British Bill of Rights. It is not likely to give greater protection to our rights and freedoms than we have now. The European Court of Human Rights is under attack by Ministers for having supposedly undermined the sovereignty of the Westminster Parliament.
I hope that my book might encourage readers to fight for the country we love - and for a more open, democratic society based on equal justice under the rule of law. Each chapter highlights the threats we face and what we must fight for.
Lord Lester is a human rights lawyer, a Liberal Democrat peer and a commentator on law and public policy