I think I may have been one of Jonathan's first pupils when he moved to Trinity Hall more years ago than either of us probably care to remember. But that's not why I am so pleased and honoured to be asked to contribute to his Festschrift. It is because it is quite rare that there is a chance to record what a difference someone makes to your life and to say thank you. For quite literally, Jonathan changed my life in at least two ways.

First, when I was an undergraduate, he introduced me to a different kind of history in which people and their motives were always interesting, but – in the case of American politics to take just one example – might suddenly also be brought to life by his amazing collection of campaign buttons.

He gave me a life-long affection for the United States. Years later, as a correspondent for the Financial Times in Washington, I would recall examples he had dredged out of what had seemed to us as undergraduates to be his gargantuan memory and which were incredibly useful in trying to explain to our readers exactly why the US was not ‘just like Britain except they speak with a different accent’.

Jonathan's fascination with the impact of individuals rubbed off on all of us. I loved the series of 45-minute lectures he created at Penn only a few years ago about the personalities who had helped create the modern world. These proved very popular with his live audiences in Philadelphia and on the CDs, which sold so well and to which we listened one summer in the car all the way from London to Perugia.

Then there is his account in his book about Italy during the Second World War of the way that the Italians, inspired by their foreign minister, artfully outmanoeuvred their German masters when it came to delivering up to them far fewer than the number of Jews they demanded, thus displaying an ability to ‘play both sides’, which is not unknown in Italy to this day!

And like so many of his former pupils, I was simply delighted by the critical – and even commercial – success of Bismarck: A Life.