So the Chancellor must be feeling quietly confident as he surfaces in order to brandish a 200-page Treasury document on why Brexit would be bad for Britain. He is taking up the pro-EU cause with gusto, warning of the "profound consequences" of leaving: that Britain would be "permanently poorer" to the tune of £4,300 for every household in the country. The submarine Chancellor is no longer trying to be subtle. HMS Osborne may now be renamed "Feary McFearyface" in this campaign.

Downing Street will be relieved to see him finally wade into the debate, after weeks of comparative silence, but what cost could this decision have on his career prospects?

The Conservative Party is a pro-Brexit beast. Roughly half of its MPs backing Out as well as over half of Tory supporters and members. This means any aspiring Tory leader could make an easy case that they understand the mood in the party they aspire to lead by backing Brexit, something their Europhile rivals would not be able to do.