A week after four people lost their lives in a terrorist attack on London, including one of our own police officers, the Prime Minister issued a veiled threat to our European partners that she was willing to use security cooperation as a bargaining chip if they didn’t give her the trade deal she wants.

Hot on the heels of this revelation, the Home Secretary added: “If we left... then we would take our information with us.” This sort of bullish approach to the future of our country’s security is reckless. Now more than ever we need to work closely with our European partners to tackle terrorism and other forms of serious and organised crime through the sharing of data and intelligence, and working together to prevent criminals and terrorists escaping justice.

The European Arrest Warrant is a clear example of how cooperation across borders has allowed justice to be delivered here at home. Recent successes include a suspected gang boss from Solihull arrested in Lithuania only yesterday, a man arrested in Belgium in connection with the murder of a man in West Bromwich and one of Britain’s most wanted fugitives, the suspected paedophile Stephen Carruthers, who was arrested after fleeing to France.

Since 2009, the European Arrest Warrant has been used to bring 800 British fugitives back to face justice in the UK. These include 41 wanted for murder, 61 for rape and three for terrorism. In each case, criminals have faced swift justice in British courts thanks to cross-border cooperation that would have otherwise taken months or years or may not have faced justice at all. David Davis saying that tools like the European Arrest Warrant are up for grabs as part of the negotiations amounts to gambling with the safety of British people and betraying the victims of these crimes.

David Davis: End the supremacy of lawmakers in Brussels

The contradictory statements Conservative ministers give from the despatch box suggest that they simply do not know what they are doing. Today, I asked the Lords Home Office Minister whether they plan to continue sharing sensitive personal information with other European Union member states for the purposes of crime prevention and detection following the United Kingdom’s withdrawal from the European Union. In her response, the minister said Britain’s data-sharing and security cooperation would be “undiminished”.

How can this be when the Prime Minister has repeatedly stated that she plans to remove Britain entirely from the jurisdiction of the European Court of Justice and from European law? Data-sharing requires compliance with EU data protection directives, over which we will soon have no say, and almost every other aspect of UK-EU crime-fighting cooperation is adjudicated by the European Court of Justice.

This fundamental contradiction is a circle that is yet to be squared and while the optimism of Government may be comforting to some, it seems like Alice in Wonderland to us. There is simply no precedent for any country outside the European free trade area to be a full member of the EU mechanisms that currently keep us safe. It’s not just the European Arrest Warrant and Europol – the Schengen Information System (SIS) means the “bobbies on our beats” can check whether someone they are talking to is a suspected terrorist or a wanted criminal in any other EU country. Amber Rudd may “take our information with us” if we fail to reach agreement, but the EU 27 would also take their information with them.

EU group leader: 'I don’t care any more' about UK interests

Negotiations will be long and arduous but the Government can’t keep ducking questions designed to clarify how it plans to solve these apparently intractable dilemmas. Today, when I stood up to question the Minister on these vital issues, I was jeered and heckled by Conservative peers, behaviour only seen in the Lords when raw nerves are exposed. It is the duty of Parliament to question and scrutinise the Government. The people deserve to know what the Government is planning, given how it will transform all our lives.

The Brexiteers talk about wanting to take back control but what they are being offered is not control by Parliament or by the people, but control by officials and ministers working in secret. The Liberal Democrats will not allow this to happen. My colleagues and I will be there every step of the way, questioning and scrutinising. The security and safety of everyone in the UK, including our brave police officers, is at risk unless we do.