The two years have been well used by the very varied forces opposing the euro to seize control of the argument. It might be impossible, at the election, to state precisely when the referendum would be held. But there's a choice to be made about language. There's another way of expressing that choice. The normal caveat must be recited.
Nobody proposes euro-entry right now, though convergence is getting closer.
The economics aren't yet right. But increasingly, economics aren't what's invading the minds of the few ministers who count. Yet Mr Blair is a British European, none more eloquent. It would push him to the margins, sine die . It would let the euro start being talked about, without putting it squarely into the election campaign.