Those paying close attention to the news will have spotted there is a Conservative Party leadership election underway.

It is of particular significance of course because the winner will immediately become Prime Minister too, which is a function of our parliamentary system of government.

Given the recent focus on the character and personality of party leaders, and perhaps especially the current prime minister, you could be forgiven for thinking we have a presidential system of government, but we do not.

Our system draws the executive from the legislature and ensures that the prime minister leads a government which, comfortably or otherwise, can achieve a majority in the House of Commons for the legislation it seeks to pass.

It follows in such a system that the prime minister is almost certainly the leader of the largest party on the commons, and when they stop leading that party they are no longer able to rely on the majority they need to lead a government and must in turn relinquish the position of prime minister.

It also follows that their successor as party leader is then best placed to be prime minister.

Sir Jeremy: 'you could be forgiven for thinking we have a presidential system of government, but we do not' (image via SWNS)

I say all this because there is much discussion at the moment, as there always is at a time of transition for prime ministers, about why party members as a relatively small percentage of the population get to choose our next prime minister.

The answer is that in a parliamentary system of government, voters choose the party they wish to govern and the party chooses its leader, whichever party we are talking about.

The alternative is a presidential system, as in the United States, the disadvantages of which perhaps I should discuss another time, but it is not the system we have, so there is nothing unusual or suspect about the application of the system we do have to the present circumstances.

The other question which is being asked often at the moment is why the current prime minister did not leave Downing Street as soon as he resigned as Conservative Party leader.

I am sure everyone reading this will be familiar with my view that the prime minister needed to resign and I am glad he has, but choosing his successor is not done overnight.

In most political parties, the wider party membership is involved in picking its leader and the Conservative Party is no different.

It takes time to organise such a ballot and MPs must first choose the two candidates who will be on that ballot.

In the meantime, the United Kingdom still needs a government.

Sir Jeremy said Rishi Sunak and Penny Mordaunt are the two best candidates (Image via SWNS and via parliament.uk)

Outgoing prime ministers, Labour or Conservative, generally stay as caretakers while their successor is chosen so, again, what is happening is an ordinary function of the system of government we have.

The alternative would be another interim prime minister for a matter of weeks until the leadership contest is concluded, which would be more disruptive.

Finally, you may be wondering who I am voting for in this contest.

My initial choice is no longer in the process, but it is worth MP's remembering that our role is to select not one candidate but two for consideration in the final round.

The capacity to run a government from day one, in the system I have discussed above, must be fundamental, along with integrity and the ability to deliver a different kind of leadership. 

All the remaining candidates have merits, but I believe the best choice to offer the wider membership would be between Penny Mordaunt and Rishi Sunak.

I am confident in the prospects of both to be successful prime ministers, but in my view Penny has the edge in representing a fresh start, so she has my vote.

(Penny Mordaunt image via parliament.uk)