The Leave campaign (see previous entry) is focusing on fuel bills this morning, with an article by Boris Johnson, Michael Gove and Gisela Stuart in The Sun.

The Remain camp, meanwhile, is warning of the impact of leaving the EU on small and medium-sized businesses.

Business Secretary Sajid Javid will cite Department for Business, Innovation and Skills analysis, estimating that 8% of 'SMEs' export to the EU and a further 15% are in the supply chains of other businesses that export to the EU.

Former England cricket captain Sir Ian Botham speaks out in favour of the Leave campaign at an EU referendum event in County Durham.

Our regular round-up of the day's main politics stories:

• David Cameron has hailed Labour's Sadiq Khan as "a proud Muslim" and "a proud Brit" as he shared a platform with the London Mayor at an EU Remain rally
• Defence Minister Penny Mordaunt has said "the public haven't fallen" for Remain's "armageddon-type scenarios" at a Leave campaign event in Cumbria
• Ken Clarke has compared Boris Johnson to Donald Trump as the war of words between rival Conservative EU campaigners escalates
• The Electoral Commission has called on Bristol city council to scrap an EU referendum how-to-vote guide over claims it favours the Remain campaign.
• A top EU watchdog has strongly criticised the European Commission over the appointment of a special adviser
• The provost of David Cameron's old school, Eton College, has attacked his proposals to ask job candidates if their parents paid for their education

The prime minister has shared a platform with Sadiq Khan just weeks after attacking him during the London mayoral campaign.

Following criticism of its voting from by the Electoral Commission, Bristol City Council spokesperson said: "This form is designed to explain the logistics of voting by post and not to suggest how someone should vote.

"The placement of the pen graphic was entirely incidental and we do not believe that anybody could reasonably be influenced by such a graphic.

"However given current sensitivities, for all future postal vote dispatches, the form and graphic will be amended."

Nick Beake
Europe reporter, BBC London

Image source, European Parliament

The European Commission has been strongly criticised over the appointment of a special adviser to its President, Jean-Claude Juncker.

Emily O'Reilly, the European Ombudsman, found the appointment of Edmund Stoiber by-passed checks on a potential conflict of interests and constituted "maladministration".

Dr Stoiber was announced as a special adviser for cutting red-tape in December 2014, but the Commission failed to make public that the German politician had disclosed he also held positions with a big insurance company.

The Ombudsman has now started a wider inquiry into the appointment process for the Commission's 40 or so special advisers, who have high-level access to EU politicians and often work for other private sector clients.

Mrs O'Reilly also criticised the Commission for an ongoing lack of transparency in its dealings with the tobacco industry. She also said the Eurogroup - the meetings of finance ministers of countries using the Euro - needed to be more open.

Commenting on EU referendum postal voting instructions, reported to have been sent out in the Bristol area, showing a pencil hovering over the Remain box, the Electoral Commission says:

No-one at Bristol Council was available for comment.

UKIP MEP Mike Hookem said: "It shows a wider problem with this referendum debate which is that people expect the establishment to use whatever tools at their disposal to get the result they want.

"If we hadn't seen endless taxpayer-funded government scare tactics then people wouldn't take one look at a photo on Twitter and say: 'It doesn't surprise me that a government body would do that'."

A UKIP MEP has called for postal vote ballot paper instructions, sent out in the Bristol area, to be withdrawn - alleging they urge voters to support the Remain side.

Mike Hookem is an MEP for Yorkshire and the Humber but UKIP says a constituent of his was alerted to the forms by a friend in Bristol.

Mr Hookem said: "Any ballot papers which have gone out with marks showing either remain or leave boxes being ticked in the example need to be recalled and the person responsible needs to be investigated.

Ken Clarke compares Boris Johnson to Donald Trump in a BBC Radio 4 Today interview.

Labour Mayor of London Sadiq Khan and PM David Cameron have put their differences aside to launch a Remain battle bus.

Ben Wright
BBC political correspondent

In a symbol of how this referendum has upended UK politics, David Cameron this morning pledged to guarantee workers' rights and lavished praise on the man he had tried to stop becoming London's new mayor. Less than a month ago the prime minister was warning about the risks Labour's Sadiq Khan posed to London. Today Mr Cameron said he was proud to share a platform with Mr Khan at a Remain rally in south-west London. The London mayor said it was important to campaign with the government on the referendum, as they launched a five-point card listing what they say voters will get if the UK votes on 23 June to stay in the EU - including access to the single market. Vote Leave said what continued EU membership really guaranteed was expensive regulation for British companies, sending money from Britain to Brussels and more countries joining the EU.

The World at One
BBC Radio 4

Image source, Maria Caulfield

Conservative Maria Caulfield has told the World at One that she hopes her party's MPs will get back to the work they were elected to do once the referendum is over - and that David Cameron will carry on as leader.

Ms Caulfield, who was elected Tory MP for Lewes at the 2015 general election, said:

David Cameron hails London Mayor Sadiq Khan as "proud Muslim, a proud Brit," as they share a platform to urges voters to back staying in the EU.

Despite the fact that neither campaign is going to form a government to deliver them, a pledge war has broken out between Britain Stronger in Europe and Vote Leave.

David Cameron unveiled five "guarantees" of what voters will get if they vote to Remain in the EU, including  "full access" to the EU single market and protection of workers' rights.

Vote Leave has hit back with five things they claim a vote to Remain in the EU would mean, including the much disputed assertion that the UK will continue to "send £350m a week to Brussels" and that voters will have to "pay out up to £43bn in tax refunds to multinational businesses", as well as a warning about red tape for businesses.

Another of the campaign's "guarantees" is that free movement of people will continue "permanently" and that Albania, Macedonia, Montenegro, Serbia and Turkey join the EU.

"We will continue to be unable to remove criminals and terrorists whose presence in the UK is not conducive to the public good," the list of "guarantees" adds. 

Vote Leave Chief Executive Matthew Elliott said:

Image source, Reuters

Vote Leave have seized on David Cameron's decision to share a pro-EU platform with London Mayor Sadiq Khan, despite questioning Mr Khan's judgement during the Mayoral contest over people whom the Labour MP had appeared alongside in the past.

UKIP MP Douglas Carswell said: "David Cameron cannot be trusted. Just a month ago he attacked Sadiq Khan as a terrorist sympathiser, yet today he hailed him as a great politician as he stood next to him on a shared platform.

"Today he trumpeted the benefits of the European Arrest Warrant but a few years ago he warned that it was dangerous and that it stripped away centuries old rights from the British people."

The former Tory MP - who was once a strong supporter of Mr Cameron - added: 

The Guardian

"Conservative party turmoil escalates with open call for Cameron to quit," is the Guardian's, external take on the weekend's attacks on the prime minister.

Its article reads: "David Cameron’s hopes of being able to avoid terminal damage to Conservative party unity after the EU referendum campaign were dented on Sunday when two rebel MPs openly called for a new leader and a general election before Christmas.

"The attacks came from Andrew Bridgen and Nadine Dorries - both Brexiters, and longstanding, publicity-hungry opponents of the prime minister - and their claim that even winning the EU referendum won’t stop Cameron facing a leadership challenge in the summer was dismissed by fellow Tories.

"But their comments coincided with the ministers in charge of the leave campaign launching some of their strongest personal attacks yet on Cameron, prompting Labour’s Alan Johnson to say that the Tory infighting was getting 'very ugly indeed'."

Speaking at the Vote Leave campaign event in Cumbria, Armed Forces Minister Penny Mordaunt says: "I think the public haven't fallen for these... armageddon-type scenarios painted that have been painted for them, trust your common sense - never mind what both camps are saying - trust your common sense and look at what is happening now.

Theresa Villiers says the referendum is "a close race" and difficult to predict.

"The Leave campaign are the underdogs," she claims. "We've got the establishment lining up against us."

But she believes that people will "recognise" that the UK would be better as "an independent, self-governing country".