Our electoral system, which sends the person with the largest number of votes in the constituency to Parliament, is designed to produce governments with clear majorities in the House of Commons – unlike systems of proportional representation which typically produce hung parliaments and make it necessary for the parties to form coalitions after each election.

As everyone knows, the result of the last election, despite the first past the post system, was to produce a hung parliament – and that, in turn, led to the establishment of the Coalition Government.

Having played some part in the formation of the Coalition, I thought that I had understood the dynamic of hung parliaments quite well – I imagined that the management of the Coalition within government would be the main political (as opposed to policy) challenge of this parliament.

During the past three years, however, I have discovered that it is in general much easier to manage a coalition between rational people than I had at first imagined.  Almost all of the difficulties the Government has inevitably encountered arose from the real world – the problems of the euro zone, the events of the Arab spring, and so forth – rather than from any unimaginable tensions within the Coalition itself.

However, in the last few weeks, I have discovered that my previous understanding of hung parliaments was insufficient.

This became clear to me when the question of press regulation arose out of the report produced by Lord Justice Leveson.

Because this happened in the middle of a parliament, it had not been one of the topics resolved in the discussions between Coalition partners at the time when we formed our partnership.  As a result, all three major political parties in parliament had to develop their responses to the Leveson Report independently.

A further result of this situation was that the voting arithmetic in parliament – which normally gives coalition governments a solid working majority – became hugely unpredictable so far as any legislation relating to the implementation of the Leveson Report was concerned.

Now, after some rather exhausting weeks of negotiation in what came increasingly to resemble something between three-dimensional chess and a Rubik’s cube, we have emerged with an agreement between all three major parties, and it is now up to the press to decide how to respond.

They say a week is a long time in politics – and I think this saying contains even more wisdom than one might suppose:  in politics, each week brings wholly unexpected discoveries about a political system with which we are apparently already very familiar but which is, in fact, evolving in unpredictable ways.