Which direction is losing for him? Neither main party leader seems to have a strong commitment either way.

I can’t see Cameron’s position being that stable in either situation, really.

Cameron publishes 4 rules for ministers who want to campaign for Brexit

Number 10 has just released a three-page open letter from David Cameron to ministers setting out the rules that will underpin his decision to allow them a free vote in the EU referendum. He set out four basic guidelines.

1 - Collective cabinet responsibility will continue to apply until the EU renegotiation is concluded. During this period, “all ministers should continue to support the position set out in our manifesto and say or do nothing that will undermine the govenrment’s negotiating position.”

2 - Ministers will only be free to dissent on the issue of staying in the EU or leaving. On all other EU-related matters, cabinet responsibility will apply.

All other EU or EU-related business, including negotiations in or with all EU institutions and other member states, and debates and votes in parliament here on EU business will continue to be subject to the normal rules of collective responsibility and party discipline.

Ministers who speak from the frontbench will be expected to support government policy. But “we need to be flexible and apply common sense”, Cameron said.

Ministers who choose to depart from the government’s recommendation [to stay in the EU, assuming that is what it is] because of long-standing and sincerely held views will not be expected directly to contradict such a position while otherwise defending government policy in parliament.

This implies that Outist ministers will not be allowed to make the case for leaving the EU from the Despatch Box.

3 - Civil servants will not be able to help ministers who want to make the case for leaving the EU.

It will not be appropriate or permissible for the civil service or individual civil servants to support ministers who oppose the government’s official position by providing briefings or speech material on this matter.

Until the last 28 days of the campaign special advisers will be able to help ministers make the case for leaving the EU, provided they want to help and that they are doing so “in their own time”. During the last 28 days separate purdah rules will apply governing what they can do.

4 - Ministers will be expected to treat each other with courtesy.

It will be very important during this period for ministers on both sides of the debate to treat each other with appropriate respect and courtesy.

Cameron said he hoped the government would remain “a united, harmonious, mutually respectful team”.