Next Wednesday MPs will be voting on what is likely to be the political question of my lifetime - whether to start the process by which the UK comes out of the European Union and Single Market.
The vote next week is on the principle of the Bill. It's not about specific amendments which will be debated at Committee stage the week after - but about whether we should vote to start the process of leaving the EU on the terms set out by the Prime Minister in her speech last week.
Along with 18 other Labour backbenchers, I have tabled an amendment which sets out the key reason as to why I believe there are fundamental problems with the Government's approach.
I might be accused of being a democracy denier but I can't sign up unconditionally to the UK leaving the European Union and the Single Market.
Whilst a narrow majority of those who took part in the referendum voted to leave the EU, the country has never been asked about leaving the Single Market and the European Economic Area (EEA).
The words Single Market weren't on the ballot paper. I can barely remember hearing the phrase "customs union" before the referendum - and yet we were fed a daily pack of lies about money which would automatically become available for the NHS, Turkey joining the EU and the "swarms" of refugees heading for our shores.
Leave campaigner after leave campaigner took to the airwaves to say this wasn't about leaving the Single Market. Page 72 of the Conservative manifesto said they would "safeguard British interests in the Single Market" and then last week, an unelected Prime Minister announces she is pulling us out of the world's largest trading bloc.
That might be what democracy means to some, but it is not what it means to me.
I acknowledge the result of the referendum but don't expect me to respect the process which led to it.
The British people, or at least MPs in the British Parliament, must have a say on whether we leave the Single Market.
Triggering Article 50 is one thing, pulling us out of the Single Market is another - but that is precisely what Theresa May wants to do.
Article 127 of the EEA Agreement sets out a process by which a country wishing to leave the Single Market can notify its intention to do so in writing, giving 12 months' notice. There should be as much scrutiny on this notification as there is on Article 50.
Our democracy didn't start or end on 23 June and we mustn't pretend that it did.
I can't stand by and watch big firms, which employ many of my constituents, announce they are scaling down operations here in favour of countries such as France or Germany - HSBC, UBS, Lloyds of London.
I fear for those whose jobs may be directly affected but I am equally worried about the wider impact on the economy. Talk to developers and they will tell you property prices are stagnating in central London - good some might say - but I fear for anyone who finds themselves in negative equity.
I fear for my home town of Swindon - a town with a massive Honda plant - an industry which has a supply chain which reaches across Europe. The ease with which businesses trade with Europe, the ease with which they sell to European consumers is threatened and nothing the Prime Minister has said reassures me about how she will, to quote the Tory manifesto, "safeguard British interests in the Single Market".
I feel like I am watching a slow motion car crash and I have to try to do something about it.
If my amendment is selected for debate, I will vote for my amendment. Irrespective of whether that happens or not, I will vote against triggering Article 50.
Nothing I have heard from the Prime Minister gives me the reassurance I would need to embark on the path of leaving the EU and the Single Market. That is where this Government wants to take us and I can't see how this is in the national interest.
Heidi Alexander is the Labour MP for Lewisham EastSuggest a correction