I presume that Brown accepts, in the abstract, that British membership of the EU is in the British national interest. He has however sometimes seemed uninvolved in the reality of being an EU member.

It would be bad for the prospects of a pro EU outcome to a referendum if Brown followed the Blair policy of not making the pro EU case forcefully.

In the only UK wide referendum in our history, in 1975, the yes side included the bulk of the leadership of our three major parties and a very enthusiastic cross party campaign. The no camp was a lot less organised than the eurosceptics are today. It was an odd mixture of left wingers like Tony Benn (who saw the then EC as a capitalist club), Labour centrists like Peter Shore (representing the early 1960s view of the late Labour leader Hugh Gaitskell, that joining the Common Market would be the end of a thousand years of history) and right wing Conservatives (at the time given little importamce compared to the dissident Labour cabinet ministers).

The overwhelming weight of political and media support was on the yes side. Leading politicians like Ted Heath, Harold Wilson and Roy Jenkins were campaigning  positively as well as warning of the bad consequences of leaving the community.

I think the British people confronted by the solemn warnings of the leading centrist political figures of the day, were persuaded to vote yes rather than risk the uncertainties of rejecting that advice.

Since 1975 the mainstream leadership of the Conservative party has moved 180 degrees on Europe. It is unlikely that any current Tory frontbenchers would be part of a pro EU campaign. On the other hand there is less division amongst the leading Labour ministers than there was in Harold Wilson's cabinet.

Nowadays, with politicians held in even more contempt than they were in 1975, and after decades of almost unanswered eurosceptic propaganda; if Brown does not campaign wholeheartedly for the EU case the prospects for it are fairly dismal.