The Queen Mother's favourite jockey is the world's favourite writer of racing tales. Dick Francis is to horses what Neville Shute was to engineering and the details of the industry in this, his 36th novel, will be welcomed by insiders while remaining accessible to newcomers.

In 10lb Penalty, the racing blends with politics. The author met John Major at Lords a year ago and the result is a delightful tale with an unusual theme: an upright son discovers his father to be a righteous man and a political success. Francis has only one irredeemably nasty character other than the person with the gun. This is the filthy Usher Rudd, a tireless researcher into sleaze.

Ben, an amateur jockey, spends the fortnight before his 18th birthday as companion to his widower father, who is fighting a marginal by-election. He is warned about the journalist: "Usher Rudd says George Juliard is not only lying about you being his legitimate son but maintains you are his catamite ... He makes up lies. He likes to destroy people. He'll do it for money if he can, but if there's no money in it he'll do it for pleasure."

The father survives his first election and lives to be attacked again: the vicious journalist comes back during the contest to be party leader and Prime Minister. It is easier to have a bad hat warned off a race course, or for the parliamentary committee on Standards and Privileges to recommend the expulsion of an errant MP, than for a lying, discredited newspaperman to be struck off for dishonourable conduct. Rudd manages to find "a market in weekly sex magazines on the edge of perversion. The motto he everlastingly lived by: SLEAZE SELLS. And where it doesn't exist, invent it".

10lb Penalty is a pleasing political thriller rather than a media morality tale. More akin to Julian Critchley than Edwina Currie, Dick Francis will give his readers a cheerful insight into a political world that is more discussed than understood. Readers will still wonder vaguely why, with everything carefully regulated to ensure the election of the fittest, there are so many nutcases in the House.

Book buyers are like floating voters. Francis knows that they have to be won over one by one, and then not disappointed. The middle market matters. His latest novel will be appreciated by the regulars, while new Francis fans will be encouraged to go through the list.