Driving has never been my favourite sport, but at least one can do it while sitting which is an advantage at my age. For those who live outside the UK the roads here are a disaster. Decades of under investment by governments all too eager to use the environment as an excuse not to invest in a modern transport system has left us with outdated, over crowded motorways which are always under repair and increasingly populated by suicidal lemmings in BMWs.

So any journey in the UK is one of incessant delays because of roadworks, usually unpopulated by anybody even vaguely resembling a road worker. Speed cameras, and notices about speed cameras abound and yet, on those sections hopefully free of them, there is a disregard for the speed limit bordering on the revolutionary. In those sections where there are roadworks, they have taken to measuring "average speed" as opposed, I suppose, to "instantaneous" speed measured as one cursingly passes a flashing light in the darkness of the wasteland between Carlisle and Glasgow.

But what average? Yours, or all the other piggy-eyed motonauts thinking only of impending destinations, or mentally trying to estimate whether they will reach the loo at the next service station in time before the essential diuretic tablets wreak their revenge?

I am pointing out, in my own way, that the word "average" is not in itself self-explanatory, and that motorway signs indicating that average speeds are limited to "30, 40 50 mph" are misleading and the practice should be stopped instantly.

For example, if one enters a piece of motorway with an "average" speed limit of (say) 50 mph then a mathematically inclined motorist could be tempted to do half of it at 100 mph and the remaining half at 25 mph. His (or her) average speed would be 50, but the variation in speed would be rather dangerous. Of course, not knowing the extent of the distance that is covered by the limited speed, it might be rather foolish to vary one's speed to achieve the average, but the experienced motorist and amateur mathematician would find a way around this using a stop watch or a voice recorder.

I am assuming of course that the "average" speed measured is calculated by taking two speed measurements, one at the start and one at the end of the limited area and then adding the two figures together and dividing by two. This is of course, an assumption, based on the belief that this is probably the limit of the constabulary's budget for radar guns and calculators. But suppose not, and that there were multiple speed cameras? Would the high/low speed motorist tactic still produce a 50 mph average? It should do, but there is another consideration - that of error of measurement. If there are just two cameras, do the errors of each measurement cancel out? Is there less error in using more than two cameras than using two?

These and other things occupied my mind as I drove northwards from the funeral of my aunt. Beethoven's Ninth was telling me to listen to the human spirit in all its glorious god-like variety of hope and fear. The last movement at full stretch is an antidote to sadness and sorrow but it cannot restore the feelings of a four year old child on his aunties knee, in front of a warm fire, as the stories from the old book came alive in the flickering firelight.