UPDATE, 18:15

The speculation I mentioned below could be wrong. Sources suggest what we are actually in for when Mrs May speaks to the cameras in No. 10 is a stark re-statement of what she has said already in the Commons. She will try to appeal directly to the public explaining that she is on their side and shares their concerns about the delay to the Brexit date.

Beyond that, it’s not clear she’s going to add much new. But many people are waiting for more. Some Tory MPs want her to give a departure date. There are DUP figures who have spoken privately of seeing the advantages in a new PM. And there are MPs from all sides who think her deal is not going to pass and Mrs May needs to free up parliamentary space and a longer extension of Article 50 to make an alternative possible.

17:28

Theresa May is giving a statement tonight in Downing Street. The Irish Taoiseach Leo Varadkar kindly announced it a short while ago in Dublin. The fact he knew and the cast list of who she is seeing beforehand suggests it could be big stuff.

The ERG are being talked to, as are the DUP. Then, around 8pm, it is expected that the PM will challenge MPs to back her deal in the starkest terms.

There’s speculation that she could spell out that defeat for her deal next week could mean a general election. Speculation too that Mrs May will, in an attempt to win Brexiteer votes, promise that she doesn’t intend to hang around as leader of the Tories and PM much longer. One senior MP who has seen her a couple of times in the last few days said; “She has hit a brick wall.”

The diary for No. 10 meetings suggests that the Prime Minister has declined a request to meet Tory MPs at the backbenchers’ 1922 Committee. There was speculation that a few MPs could use this occasion to tell her to her face that she must name her departure date. “Her authority is shredded,” one minister told me this morning. It’s a line you hear with variations in the language quite a bit.

The flurry of anticipation came as the European Council President Donald Tusk was spelling out in a brief statement in Brussels that the short extension of Article 50 could only be considered if the UK had passed the deal. He left unspoken what might happen if the deal didn’t pass. The alternative, longer delay to Brexit which Theresa May pointedly didn’t ask for in her letter to European Council President Donald Tusk, would come with big strings attached as Michel Barnier explained yesterday: a big democratic event like a general election or a second referendum would have to be held to justify such an extension.