Here's a late afternoon roundup of Monday's big political stories:

• Theresa May has said that "nobody wants to return to the borders of the past" during a visit to Northern Ireland
• Scotland's First Minister, Nicola Sturgeon, has outlined her next steps in attempting to secure Scotland's position in Europe
• MP Sarah Champion, who quit Labour's front bench during a revolt against Jeremy Corbyn has been reinstated after asking for her old job back
• Sir Philip Green and others who "got rich" from BHS have been blamed for the retailer's collapse in what MPs called the "unacceptable face of capitalism"
• Activists engaging in abusive behaviour online or at meetings will not be able to vote in Labour's leadership contest, the party's general secretary has said
• Voting has begun in the contest to elect a new leader of the Green Party in England and Wales

Radio 4 PM programme

Dr Lee McGowan, who lectures in European politics at Queens University in Belfast, says talk of border controls between Northern Ireland and the Republic of Ireland reminds people of "the dark says of the 1970s" when there were watchtowers and checkpoints.

If the UK were to leave the EU and have no single market access, unlike non-EU Norway, for example, there is likely to be a "hard border" but even if something like the Norway model is reached, "there would still be border controls in terms of customs posts", Dr McGowan says.

The "tricky question", he tells Radio 4's PM programme, is that the nature of that border cannot be decided in a bilateral agreement between the two countries. It would need the agreement of other EU member states. The Republic of Ireland, which will remain in the EU, could play a key role in persuading them, he adds.

While Dr McGowan thinks "we're not talking in terms of any return to violence" in Northern Ireland, Brexit "does have the potential to unsettle relations between Northern Ireland's communities and political parties".

Radio 4 PM programme

Business leaders in Wales call for a taskforce to deal with the implications following the referendum result, as the first minister promises a £5m jobs and growth fund.

A spokeswoman from Sarah Champion’s office has spoken to her and she’s confirmed she’s “retaken” her previous job:

Theresa May has held an hour-long meeting with Conservative MEPs in Downing Street to discuss what have been called "red lines" in negotiations about leaving the European Union.

The Tory leader in the European Parliament, Syed Kamall, said afterwards there would be "months of negotiations" before Article 50 - the process by which a member state may leave the EU - was invoked.

He said: "We were starting to talk about the different areas of negotiations, not coming to any conclusions yet.

"I don't think you can say what will be and what won't be on the table. Neither side really have agreed their red lines. The British government needs to discuss its red lines across all departments. At the same time in Brussels they haven't decided what their red lines will be in any negotiations."

Mr Kamall said he didn't know how long the process would take and that today's meeting would be the first of many.

BBC News Channel

Norman Smith says "team Corbyn, as you might expect, are overjoyed" that Sarah Champion is rejoining the frontbench fold.

The question is whether she's "a lone dissident" or whether the revolt by Labour MPs against Jeremy Corbyn's leadership is "crumbling", he adds.

Norman Smith
Assistant political editor

Labour leader Jeremy Corbyn has agreed to give Labour MP Sarah Champion her frontbench job back - after she asked to be re-instated.

Ms Champion - who was a shadow Home Office minister - resigned the position along with many other Labour frontbenchers following the vote of no confidence in Mr Corbyn.

However, she has now asked Mr Corbyn for her job back. Mr Corbyn's office said the Labour leader had now written to "welcome her back". 

The move will be seen as a significant coup for Mr Corbyn and will fuel hopes that the revolt among Labour MPs may crumble. A Labour source said: "You saw what happened when the first miners went back to work, so let’s see what happens.”

Theresa May has visited Northern Ireland for the first time since taking over as prime minister.

As home secretary campaigning to stay in the European Union, she described it as "inconceivable" that Brexit would not lead to changes to the border arrangements between Northern Ireland and the Republic of Ireland.

It is important because once the UK leaves, it will be the only land border between the UK and the European Union.

Read more.

BBC News Channel

Shadow business secretary Jon Trickett adds his voice to those calling for Sir Philip Green to lose his knighthood and to pay to cover the deficit in the BHS pension scheme.

He tells the BBC that reforms floated by Theresa May, such as workers' representation on company boards and more powers for shareholders are "measures which we announced in our last election manifesto".

Mr Trickett says Labour wants to "celebrate great British successes" and "reward good businesses but... crack down on those handful of companies and individuals that misbehave".

Could there be cross-party consensus?

The shadow business secretary says that during the Conservatives' time in power "we've seen a whole series of quite serious scandals and I'm wondering if they have the will to deal with this". However, if the government showed willing it would "have cross-party support", he claims.

Esther Webber
BBC News

Responding to reports of problems with Labour's mayoral candidate selection process in Manchester, a spokesman for contender Tony Lloyd said he was "happy with the procedure" and the distribution of ballots was "in line with what we would have expected". 

A rival campaign told the BBC Mr Lloyd was not calling for an extension to the selection deadline "because he is hoping for low turn-out". 

Mr Lloyd's spokesman rejected this, saying his team were "active campaigners - the only campaigners out knocking on doors every day, and we have fought to increase the number of people who can take part in choosing Labour's candidate". 

A small number of nominations in the leadership from constituency Labour Parties race show eight CLPs have nominated Jeremy Corbyn while just two have backed Owen Smith.

CLP nominations gave an early indicator of Jeremy Corbyn’s popularity within the Labour Party during last year's leadership election.

As the map shows. this is only a tiny sample of the total number of CLPs and more nominations are expected - though following the suspension of all CLP meetings by Labour's national executive, it is unlikely that many CLPs will nominate this time.

The Labour Party has confirmed it received a complaint about delayed postal ballots for the selection of mayoral candidates in Greater Manchester and Liverpool.

A Labour spokeswoman said: “Any extension of a deadline for voting would be a matter for the National Executive Committee.”

BBC News Channel

Labour's National Executive Committee is to set up a "balanced" panel of its members which will look at claims of abuse and intimidation. The party's general secretary, Iain McNicol, has said that too much abuse is going on "and it needs to stop".

BBC political correspondent Iain Watson says when Mr McNicol made that statement, "there were accusations from supporters of Jeremy Corbyn that he was going to be carrying out some sort of witch hunt, as they put it".

Therefore, Mr McNicol says the panel will be balanced between supporters of Jeremy Corbyn and opponents in an effort to to "reassure people".

Iain adds:

BBC Radio 4

As a rule of thumb, parliamentary whips are silent. They cannot afford to hold a view in public, they don't do media. Instead they hold a mysterious, shadowy status. But in this programme, it's a status which political reporter Giles Dilnot uncovers.

As Giles discovers, their role extends far further than just disciplinarian. They are the lubricant in the system, the wheels on the vehicle, the stage managers to Parliament's stage.

The World at One
BBC Radio 4

Esther Webber
BBC News

Labour is in the process of selecting mayoral candidates in several city regions - and as Carole Walker reported earlier, the party is facing calls to extend the timetable after delays in sending out ballot papers.

A source within Andy Burnham's team has told the BBC that the delays to postal ballots will particularly hit those who do not have a means of receiving an e-ballot - estimated to be 25% of those eligible to take part in the vote in Manchester.

And many people who should have e-ballots also say they haven't been sent them, according to the source. 

All six candidates' campaigns in Manchester and Liverpool were asked to sign a letter calling for an extended timetable, but one mayoral hopeful - Tony Lloyd - reportedly declined to add his name.

There are fears within Labour that these problems could be affecting mayoral selection votes across the country and not only in the North West.