AS Conservative MPs cast their votes in the first leadership ballot today, the contest is overshadowed by something unsaid.

In the past few weeks all four candidates' have expended thousands of words, at the Blackpool conference, at Westminster, and in television and newspaper interviews, trying to sell themselves to party and country.

Yet the focus remains on the single word which remains conspicuously absent. And only David Cameron knows whether it is "yes" or "no".

Tonight we ask whether it matters if Mr Cameron experimented with drugs as a student, as his stubborn silence on the issue implies.

North Yorkshire MPs of all colours say it does not. Both John Greenway and Phil Willis suggest that a knowledge of the real world - and the real world is full of drugs - is a good thing for an elected representative.

True enough. No one would want squeakily sanitised MPs adjudicating on our behaviour from within a bubble of self-righteousness.

Perhaps more pertinent than David Cameron's youthful indiscretions is the question of honesty. A straight question was put to him, and he has failed to give a straight answer.

This has had the effect of whipping up a storm of intrigue over what, in Mr Bayley's words, the Tory leadership contender has to hide.

It would have been a refreshing antidote to the spin of Tony Blair if Mr Cameron had been open about any drugs experiences, and what he had learned from them. He might have discovered that voters would tolerate and even respect such an approach.

Updated: 09:19 Tuesday, October 18, 2005