A few avid Brexiteers may still believe that leaving the EU after four decades can be done in the manner of Tommy Cooper, "just like that". As the appearance of the first of eight Brexit Bills demonstrates, it will be no easy task.
Quite apart from negotiating our new trading and diplomatic relations with 27 other countries, there is the small question of untangling thousands of regulations that affect our everyday lives.
Consumer protections against unsafe goods. Quality checks on food and drink. Harmonised building sizes, so that parts can be changed. Employment rights, to keep workers safe and properly rewarded. Banking systems which help money move swiftly with the account holder. Insurance cover, so we can drive abroad without extra paperwork. Child protection measures, to ensure maintenance and access rulings are upheld across the continent.
It was to deal with these and other everyday matters that the government produced its European Union (Withdrawal) Bill - loosely referred to as the 'Repeal' Bill.
The Bill sets out to achieve four things. To repeal the 1982 Act, which gives affect in the UK to cross EU regulations. To 'domesticate' those regulations so that similar ones continue in place the day we exit. To bring into law anything needed as a result of the 'divorce' negotiations. And to give legal approval to the end of the 'Article 50' process, i.e. Parliament saying "we're out".
While the first of these is legally clear, the second - empowering the government to use secondary legislation to entrench existing rules into UK law - is necessary so that business and everyone else can work as before. However, the volume of such legislation - some thousands of statutory instruments (SIs) - raises serious questions as to whether Westminster and Whitehall have the ability to ensure these are fit for purpose.
More serious are the other two parts of the Bill.
Clause 9 will allow the government to use SIs for issues arising from the negotiations. Legislation that comes under far less scrutiny than that in primary bills, and can only be approved or rejected rather than amended.
Not only will it mean using this power for something new but it may also be deployed at a very late stage, between the end of the negotiations and the day of departure. Never a good time to make law, but the proposals are fairly open about it all: "A Minister ... may by regulations make such provision as the Minister considers appropriate for the purposes of implementing the withdrawal agreement."
The government says these powers may not be used to impose taxation. Yet it admits new quangos might be needed to take over functions hitherto done by the Commission or EU agencies, and these will need fee-charging powers. Plus powers to introduce new criminal offences, provided they couldn't lead to a sentence of more than two years. There are also plans to bring some EU competencies back to Whitehall which should by rights go to the devolved administrations, prompting Wales and Scotland to threaten to withhold their consent.
There remains the interesting, fourth, assertion that the Bill will give effect to the act of withdrawal from the EU and Euratom - the end point of the triggering of Article 50. Perhaps, but it also says that this is quite separate from the promised vote in both Houses on 'the deal'. And it will take a lawyer to advise which of these actually authorises Ministers to conclude the final withdrawal agreement.
Lastly, the Bill specifically deletes reference to the Charter of Fundamental Rights that has set the context in which EU regulations are implemented. Without this, there will be no framework for a court to judge whether the new laws are appropriate and being upheld. It's hard to see why the Charter couldn't be included in the Bill, given ministerial claims that it adds no new rights which aren't elsewhere in UK legislation. Doing so would make it clear that all regulations brought in by SI should be read in the context of these vital citizens' rights.
This first of eight Bills will test the government, the civil service and Parliament as to whether the UK really can untangle four decades of close cooperation and rule making while at the same time negotiating and legislating for a completely new relationship with our near neighbours and close trading partners. It will also test whether Ministers are willing to talk, listen and compromise in order to build a consensus for a route out of the EU.
As the Opposition in the Lords, we have been clear there are no blank cheques - and we will not take on trust bland assertions that nothing of consequence is being squeezed through by the secondary 'back door'. We will do our usual job of exposing shortcomings, demanding change and scrutinising legislation in whatever form, and giving both the Commons and the government the opportunity to think again. It's the least that will be expected of us.
Baroness Dianne Hayter is Shadow Brexit Minister and the new Deputy Leader of the Labour Peers Group