The day after I suggested that the House of Lords may try to delay Britain’s exit from the European Union, my inbox filled with angry rants against such an attempt to thwart the will of the people. They decried the idea as an outrage against democracy and raged against “the metropolitan elite”, that phrase much bandied around in the anti-EU media. Gradually, however, more reasoned messages of support have been landing, reflecting the despair felt by many in this country, and not just in the metropolis.

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The overwhelming message from these people is that the country should not take such a momentous decision without knowing what it entails.

“Brexit means Brexit,” the prime minister repeats. She might, with as much clarity, declare that “lunch means lunch”: that could translate as a sandwich al desko or a three-course feast at a top restaurant.

We don’t have a clue what Brexit means and it is surely not unreasonable to suggest that, once we do, the electorate should have a chance to decide whether it really favours that over membership of the EU.

The difficulty with this argument is that, by the time that there is any clarity on the terms of a deal, it may be too late to turn back. Once the UK has triggered the exit process by giving notice under article 50 of the Lisbon treaty there is no provision for withdrawing that notice. The treaty is clear that, once a member state has given notice of its decision to leave, there is a period of two years within which terms can be agreed and, failing that, the state is officially kicked out of the club.

The only possible alternative is that the two-year period should be extended but that would require a unanimous decision of the European council. It may be that our fellow EU members are prepared to show such tolerance but they may judge us to have had one tantrum too many, and bring down the guillotine. I don’t think we should take that risk.

The referendum was only advisory. The decision to leave the EU is made when article 50 is triggered. The government’s position, currently being fought out in a legal case destined for the supreme court, is that the prime minister has the power to pull that trigger by herself. Eminent constitutional lawyers argue convincingly both for and against this proposition. But whatever the law says, politics surely dictates that there should be a vote in parliament before such a far-reaching decision is taken.

Withdrawal from the EU is too big a step to be taken by one individual exercising the royal prerogative

Withdrawal from the EU will impact on our children and theirs. It has implications way beyond the economic ones on which so much of the debate revolved. It is too big a step to be taken by one individual exercising that wonderfully British construction, the royal prerogative.

The sovereignty of parliament must prevail. It is central to our democracy and needs to be nurtured. There are far too many examples around the world of what happens when too much power is vested in any individual.

The ardent Brexiteers contend that the people have had their say and immediate action should follow. Yet some who voted out are already voicing misgivings. This is hardly surprising, given the nature of the campaign and what has since transpired. That extra £350m a week for the NHS promised by the leave campaigners proved as reliable as Andrea Leadsom’s CV. The remainers failed to make a positive case for the EU – did anyone mention the Erasmus project? They were squeamish about discussing the peace dividend from Europe.

But while the hike in mortgage rates that George Osborne threatened if leave triumphed is unlikely to follow on Thursday’s interest rate cut, the other dire predictions about the effect on the economy are already proving distressingly accurate. This week, surveys on the service and manufacturing sectors signalled the steepest fall in the economy since the height of the financial crisis. The drastic slump in the value of the pound is taking its toll on holidaymakers and, while optimists argue it should boost exports, that ignores the effect on manufacturers who have to import their materials.

Is this really what 52% of British voters wanted? The valedictory message from the Vote Leave campaign provides an eloquent explanation of what motivated many of the out voters, and it was not to do with Brussels and its many flaws. “Vote Leave took on almost every force with power and money and we won,” it boasts, insisting that “We spoke for those on PAYE”.

For them, it was a vote against that perceived “metropolitan elite”. And it is true that there is widespread anger in the country about inequalities generally and executive salaries in particular. That should not constitute a reason for pulling the country out of the European Union. It is incumbent on parliament to take a more measured view of the issue. Both David Cameron and Theresa May have talked of “involving parliament”, but that might mean nothing more than yet another debate on the issue. That is not enough.

Insistence on an act of parliament before article 50 is activated buys time. During that time, the EU itself may begin the reforms that are so badly required. The UK is not the only country that wants change, and there are various proposals for how the principle of free movement could be retained while bringing in some limitations. Any such change would be reason enough to stage the second referendum many would like to see.

It is not the role of an unelected House of Lords to thwart the will of the people, but it is our job to ask the government to think again should we believe it is making a mistake. The Commons may be cowed by the narrow majority of the referendum but, on this vital matter, I believe the Lords should urge caution. I hope that there would be a majority prepared to stall the bill through the one session of parliament that is possible before the Parliament Act can be invoked. This would be a break with the convention that the House of Lords does not stand in the way of a manifesto commitment. But when it was a manifesto commitment to plunge into the unknown, I for one am prepared to go against convention.