UK and EU flags flying outside the European commission’s office in London. Photograph: Odd Andersen/AFP/Getty Images

So it looks as if there could be a second legal challenge to the government’s decision to leave the EU. British Influence, the pro-European group, is arguing that while people voted in the referendum to leave the EU, that is not the same as leaving the European Economic Area (a slightly wider group, including three other countries in the single market but not in the EU), and it is threatening to go to court over the issue. My colleague Anushka Asthana has the details here.

British Influence is saying MPs should have a vote on the decision to leave the EEA. But, on the Today programme this morning, Sir Michael Fallon, the defence secretary, said parliament was already being consulted.

MPs and peers are having a say at the moment. We had a debate just last week on Brexit and how it affected the future in Britain. Ministers like David Davis, who heads the [Brexit] department, are regularly subject to questioning in the Commons. It is right that parliament should be involved in tracking the negotiations. But what we are not going to do is open up our entire negotiating hand, precisely because it concerns a lot of the complexities of the sort we are going to be discussing with the Polish delegation today.

When it was put to him that the new legal challenge could delay the Brexit process, he insisted it would not. He told the programme:

If we hear more on this topic, I will post it.

Here is the agenda for the day.

9.30am: Nick Clegg, Anna Soubry and Chuka Umunna speak at an Open Britain event where they will publish a report saying leaving the single market would be damaging to almost every sector of the British economy from manufacturing and energy to retail and financial services.

9.30am: Matthew Elliott, chief executive of Vote Leave, speaks at a UK in a Changing Europe event.

10am: The OECD publishes its Global Economic Outlook report.

11am: Number 10 lobby briefing.

11.15am: Ukip announces the result of its leadership election.

12.15pm: Theresa May meets her Polish counterpart, Beata Szydlo, as part of today’s UK-Poland summit.

2.45pm: May and Szydlo hold a joint press conference.

4.15pm: Sir Mark Lyall-Grant, the national security adviser, gives evidence to the parliamentary joint committee on national security strategy.

As usual, I will be covering the breaking political news as it happens, as well as bringing you the best reaction, comment and analysis from the web. I plan on posting a summary at lunchtime and another in the afternoon.

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