It's stating the obvious I know, but Peter Jones is a constant joy - except of course to those who are enemies of the Classics. He gave the opening lecture at the ARLT Summer School in Sedburgh this evening, full of enthusiasm for Libya's Roman sites, principally Lepcis Magna. He visited it a couple of years ago, and if he had his way, 9 a.m. tomorrow would see us all forming an orderly queue in the local travel agents to book our holidays there. Bringing our students too, perhaps.

He cleared up something that has bothered me from my schooldays - and those, my dears, were many years ago - and that is, why the place is sometimes called Lepcis Magna, sometimes Leptis Magna. Apparently the real name has always been Lepcis, as witness loads of inscriptions all over the town; but there was a nearby settlement called Leptis, and Roman historians assumed that both towns were called Leptis (which sounds more like Latin anyway) and that one was Magna and the other Parva. The 't' wrongly put instead of 'c' was all the fault of those historians. So that's clear at last. Thanks, Peter.

We were treated to a clear and entertaining history of Libya during the 20th century, culminating in the fact that the Roman sites have been brilliantly excavated and restored by Italian, then British and Italian, and then Libyan, archaeologists. We learned why Colonel Gaddafi never let himself be promoted to a higher rank (a diplomatic secret, that), and more importantly that the Colonel is keen to encourage tourists.

Such is Peter's skill as a speaker that we hung spellbound on his words as he recited a long list of statistics and calculations about how many hours a lamp with a single wick would burn on a litre of olive oil (136 is the answer), how many lamps were likely to have been burning away in the city of Rome, how many litres of olive oil the average Roman would have needed for cooking, washing etc, and finally how many litres the whole city of Rome would have needed in one year. To meet this need, what area of olive plantations would have been required (a third the size of Kent is the answer to that one). And how many litres would have gone through the gigantic presses at Lepcis in a good year? I think the answer was (though by that time my head was reeling) that Lepcis could have supplied half Rome's needs. Oh, and I forgot to report that olive oil came in three pressings, the early (July to August), used in medicines and cosmetics, the September when the olives were ripe (good for eating), and the December when they were black (only good for cooking and washing). Or have I got that the wrong way round?

So much detail that could have been tedious, delivered in an intriguing and entertaining way. I'm reminded of W.S. Gilbert's modern Major-General with his

"many cheerful facts about the square on the hypotenuse."

And apparently - I keep remembering other gems - the Spartans couldn't, physically could not, have destroyed the Athenians' olive trees during their invasions of Attica. And if they had, new trees would fruit in five years, not the 20 years we were told at school.

Did I mention that Peter Jones has recently revised Rieu's translation of the Iliad, and that this new Penguin book helpfully tells you what is happening with little indented summaries that distinguish Greeks (Roman type) from Trojans (Italic type), and mortals from GODS (capitals)? What will the man get up to next? Well actually he's producing a new post-GCSE Latin reader, with helpful and (would you know it?) witty notes. He considers two ways Deucalion and Pyrrha after the flood might repopulate the world, 'the usual method' or the way Prometheus used, moulding humans from clay, which Peter calls 'a rather less exhausting and more immediate solution.'