Prime minister's questions
When it comes to party leaders Sir Ming Campbell is the easiest to persuade onto Newsnight. Scotland's new First Minister Alex Salmond is also rarely unavailable, though that may change. But the very biggest beasts have been only rarely sighted on Newsnight in recent years.
Last night we had Tony Blair, which was great. It had been a long time. But much as we'd have liked a no-holds-barred affair with Jeremy Paxman on matters ranging from the Iraq war to Lord Levy, that, so far, hasn't been on offer. Instead our tenacious environment specialist Roger Harrabin got the gig, on the circumscribed area of climate change. And if the PM thought he was going to get some soft bowling the record emphatically shows otherwise. (Watch the full version here).
The episode illustrates the care with which the party leaders' media appearances are picked these days. These days we're in competition with Blue Peter, GMTV, Richard, Judy and more for interviews with our leaders, and frankly they seem to be winning.
Take David Cameron. Some observers felt he came very well out of the "slippery nipple" encounter (which you can watch here) with Jeremy just before he became Conservative leader. But despite regular invitations to repeat the experience in an imaginative array of formats, more than a year later our wait goes on.
And our next prime minister, unencumbered by the need to go to the country, has so far not felt the need to spell out his vision on Newsnight, though we remain hopeful that will soon be addressed.
There is of course no constitutional imperative to appear on Newsnight - would that there were - but we'd like to think there is a convention that if you want to be prime minister you should.
Watch this space.