If I were Prime Minister: I'd introduce a 70% tax on salaries above the top level in the public sector

Our series in the run-up to the General Election – 100 days, 100 contributors, but no politicians – continues with the economist and author

Here is an agenda that would upset so many vested interests and challenge so many shibboleths that it has zero chance: it would unite left and right in outrage. But it would do a lot of good.

Tax: Introduce punitive tax rates of 65-70 per cent above the top levels of public sector salaries (which have at least some element of social acceptance).

The purpose would not be to raise money but to signal disapproval of incomes that undermine social cohesion. Forget the increase 45 per cent to 50 per cent; it creates the false impression that other people can finance public spending, whereas spending has to be sanctioned by the taxation of ordinary people.

End relief for buy-to-let, so that young people are not outbid by the affluent retired. Abolish non-dom status, and tax retrospective capital gains on property owned by non-residents.

Shrink the finance and legal sectors by a combination of taxation and regulation. Their activities are predominantly rent-seeking rather than productive and they siphon off talent that could otherwise be socially useful.

Public spending: A big increase in infrastructure spending partially offset by a reduction in welfare spending. At current interest rates, redressing our acute infrastructure deficit makes overwhelming sense. However, it has to be made clear that an increased deficit is not a reflection of political weakness: welfare spending could be reduced, for example by limiting child support to the first two children and a lower income threshold than at present.

Education: Introduce free, publicly run pre-school education for everyone, from age 2.5 years (as in France).

Run a major child literacy campaign targeted at families. Sack the bottom 5 per cent of secondary school teachers, measured by their value-added (yes, these things can now be measured accurately and without social bias).

The evidence that the worst teachers do huge damage to children is chilling. Raise university fees, using the money to expand the number, quality and status of apprenticeships, aiming for the German model. (Reducing university fees is about the most regressive policy it is possible to dream up).

Health: Stop the pretence that the NHS is the envy of the world, and switch to the French system which works much better. In enables genuine patient choice.

Constitution: Our political system is now so abusive of basic democratic principles that the legitimacy of political power will rapidly erode. In needs urgent and deep reform.

Introduce PR to restore a defensible relationship between votes and seats. Introduce a normal federal system (like many other countries), in which each component of the UK has the same powers while a federal parliament controls macroeconomic and international policies. Introduce the Primaries system for the selection of party leaders.

Sir Paul Collier's latest book is 'Exodus: Immigration and Multicuturalism in the 21st Century'