Ian and football refers to the running joke on Have I Got News For You which is that Ian Hislop is absolutely oblivious to all aspects of the world of Football. He often doesn't know players, managers or any other part of a football related story which comes up in a program.
A subversion of this is that sometimes , as a joke, Ian display highly detailed information about a recent Football game to the complete surprise of Paul and the other guest. One such incident led Paul to say:
(sentence with a blank: "____ would have been surprisingly avant-garde for rural Highbury")