I have to agree totally with the excellent detailed reviews already written. Professor Dr. Dr. von Igelfeld is one of McCall Smith's greatest creations, and it has been far too long since his first appearance many years ago. The hapless Professor undergoes yet more hilarious misunderstandings; every encounter with his academic colleagues in Regensburg seems to be burdened with slights, intended or otherwise, and the introduction of Herr Huber, the librarian rather too engrossed with his aunt in her nursing home, made me burst out laughing at times, as did the detailed description of Igelfeld's fall from the very top of the Devil's Needles to surely certain death.
You have to wait until the very end to find out the unusual use for olive oil, but it is worth the wait.
Speaking of which, please AMS, don't leave it so long for this marvellous character to appear in print once more.
Highly recommended for everyone looking for gentle humour of high quality.