The most interesting thing about "In St. Augustine's Chair" last night on Radio 4 was the fact that it was broadcast at all. Anthony Howard's headline-generating interview with Robert Runcie had already been heard and cut up into bite-size pieces as part of The Purple, the Blue and the Red, Howard's history of recent relations between the C of E and the state in the last 15 years or so, which was broadcast last month. What we got here was a kind of director's cut.

The extended interview didn't contain anything hugely new - all the big, worthwhile beans (the former archbishop's comments on his relationship with Margaret Thatcher, and his admission that he had knowingly ordained homosexual priests) had already been spilled. You did get more of Howard's questions, more of the pattern of Lord Runcie's replies, and a stronger feel for how the conversation was conducted. But really, this programme was simply Howard's way - and his producer, Mark Savage's - of nudging the listener, and pointing out what a damn fine interview it was.

Which it was. It's rare for a public figure to unburden himself as frankly and amiably as Lord Runcie did here, to offer such unqualified admission of past failures - a failure to recognise how deftly Mrs Thatcher's message caught the public mood, for instance - and a little self-congratulation was in order. The real reason for noticing the programme, though, is its air of melancholy. "In St. Augustine's Chair" was an encounter between representatives two of great but beleaguered liberal institutions - the Church and the BBC. You doubt that such an interview could happen again; it's worth savouring.

Another of the great liberal institutions, Tommy Boyd, is still holding forth over on Talk Radio. His opinions are often perfectly reasonable; it's his reasoning that seems eccentric. Yesterday afternoon he was on about smacking children - he is against it, on the grounds that it is a form of bullying. "Wouldn't it be an interesting idea," he suggested, "if children were born 24 feet tall. Mmmmm? Mmmmm?" For the second half of the programme he switched to global warming - which he sees as a challenge to our optimism.Why do scientists never look at the silver lining, he wondered - why, soon we'll all be able to grow bougainvillea. If I had a 24-foot child, I would send it round to Tommy Boyd's house to put him in a large sack. I haven't got any further than that yet, but when the fantasy is fully developed I'll let you know.