What is the advantage of letting sitting MPs work for lobbying firms? What are the pluses of that, for the country? Because we do allow it, so I’m assuming there must be some upside.

After all, there are clear advantages to many things we don’t allow: smoking on petrol station forecourts, for example. Allowing that would mean, if you’re addicted to smoking, or enjoy smoking, or think smoking makes you look cool, you could do it while filling your car with petrol, polishing its bonnet, going to buy snacks, checking the tyres and so on. You wouldn’t be inconvenienced by either the discomfort of nicotine withdrawal or a hiatus in the image of nonchalant suavity that having a fag in your mouth invariably projects.

And the same goes for those essaying auras of Churchillian defiance and grit, or Hannibal from The A-Team-style twinkly maverick leadership, to which a lit cigar clamped between the teeth can be vital, particularly if you’ve got a weak chin.

Similarly, if you’re a pipe-smoking detective of the Sherlock Holmes mould and are, perhaps, investigating a crime on a petrol station forecourt, or merely passing across one while contemplating the intricacies of a non-forecourt-related mystery, you wouldn’t have to suffer a lapse in the heightened analytical brain function that you’ve found smoking a pipe crucial to attaining. Interrupting such processes to buy petrol may cause murderers to walk free.

And then there’s the possibility that allowing smoking at petrol stations will marginally increase overall consumption, and therefore sales, of tobacco products – all the Holmeses and Churchills and Bonds will be able to get a few more smokes in before they die of cancer – which would slightly improve trade and GDP, and so create jobs.

Maybe Duddridge just pops in once a month and is a master of clearing photocopier jams.

Nevertheless, I am not, on balance, in favour of allowing smoking on petrol station forecourts. The manifold advantages are, in my view, outweighed by the several disadvantages: passive smoking for non-smoking users of the forecourt, nicotine staining of the underside of the canopy, and various others I can’t currently bring to mind.

But you’d think, in a system that flattered itself as non-mad, as I believe the British one still does, practices that are legal would be bristling with more boons for the community than those that aren’t. That’s got to be the vague rule of thumb, right? So then, what are the good things about allowing sitting MPs to take paid work from lobbying firms? What are the upsides to that?

The downsides are as hard to miss as a few hundred thousand litres of subterranean petrol suddenly exploding. Let’s take an example from the news last week. It was reported that James Duddridge, a Tory MP who was minister for Africa from 2014 to 2016, is being paid £3,300 for eight hours work a month by a lobbying company called Brand Communications.

It’s one of the few lobbying companies not to have signed up to the industry’s code of conduct, which prohibits employing sitting MPs. You may say that makes it a nasty firm, but I don’t blame it. Why would it sign up to extra rules if it doesn’t have to? That’s like volunteering to observe a lower speed limit than the one prescribed by law.

The law is absolutely fine with Duddridge’s little earner. Former ministers’ jobs just have to be approved by the Advisory Committee on Business Appointments, itself described by the Commons Public Administration and Constitutional Affairs Committee as a “toothless regulator” (these committees are so bitchy!), since it has no statutory powers of redress. Then again, as its rulings are almost invariably “That’s fine”, what powers does it really need?

Duddridge himself says it’s all legit because Brand Communications is “not a public affairs company”, but the company’s website says “James will bring his deep knowledge of Africa, experience of operating at the highest levels of government and extensive networks to Brand Communications”, which sounds a bit public affairsy to me.

But I don’t know: maybe it’s fine. We can’t know it’s definitely not fine. Admittedly, according to the Times, the head of one of Britain’s leading lobbying firms called it “an appalling example of bad practice”, and the chairman of the Association of Professional Political Consultants said, “MPs should not be lobbyists. It is wrong to be a lobbyist and make the law at the same time,” but maybe it’s still fine.