For the price of a bag of crisps we can clean up politics...

Our economy is worth £3trillion a year. If it were a company it would be a monster. Even as an entire country it's a whopper, the sixth biggest in the world. We employ an army of civil servants – 500,000 of them – to run this huge enterprise.

That costs us £20billion a year. They do the bidding of the government of the day. Here's where it goes sideways – we allow our political parties to be funded by private money. The people with their hands on the steering wheel of our entire economy are privately funded.

It's a system of inherent risk, risk of self-interest over national interest, of government decisions being made to suit wealthy donors. And it's a system of inherent suspicion. Suspicion of motivation, of influence in decision making – it's corrosive to our politics, to our national conversation. We're never more than five minutes away from one allegation or scandal, or another.

Perhaps more than any other single factor, the way we fund our politics has undermined belief in politics itself. And that's a very high price to pay indeed. And for what? Over the last five years the total of all donations to all parties is a mere £50m per year.

We struggle to contain the donor system, to prevent foreign and corrupt money entering our politics, most recently crypto donations – which by their very nature and design – are untraceable.

We play 'whack-a-mole' when we seek to constantly adjust to new funding loopholes – in our vain attempts to control where the money comes from. While we have no tools and no chance to control what influence the money given by donors actually has. Surely the answer to this is a simple ban on all donations.

As a Labour donor I've met a handful of major donors and I am certain that not a single one of them asks for or expects a single thing in return – me included. We all want a progressive government and we recognise the system we operate in requires people that can, to contribute to the funding needs of our party of choice.

But it's not the same with other parties, most noticeably right now with Reform, accepting huge sums in untraceable currency, enjoying the threat of even greater funding from some of the world's most unsavoury, foreign billionaires. It's bad enough we allow foreign ownership of our press – foreign money in our politics is rightly banned, but hard to prevent.

We've just had 14 years of Conservative government in which there were endless scandals involving money and influence. Robert Jenrick may be the poster child for this with his unlawful planning decision made for a donor when in government and more recently with allegations he took foreign money when running for the Tory leadership. Cash for influence is a Tory thing, but not uniquely.

The unions that fund Labour openly demand influence on policy and stamp their feet when they feel unheard – not for self gain as such but influence in return for funding nonetheless.

£50million a year in private money controls the £20billion a year civil service army that runs our £3trillion economy. That's how it boils down – for the want of a trivial sum in public funding we commit surely the world's greatest act of false economy, given the harm it brings.

But if you talk to politicians about the idea of public funding for our politics, they'll tell you the public don't want it. But guess what, those politicians are out of touch. Our opinion poll shows a clear and overwhelming desire from the public to put right this running sore of a problem that causes us such great harm.

A significant majority of the public say yes to public funding, to the end of private influence, perceived or actual – an end to the endless suspicion and corrosion and undermining of public life.

It's not just because of what is at stake, of the opportunity we have to properly clean up politics, once and for all, but because we can do so at such a small cost – no more than a packet of crisps per person per year.

A tiny, tiny cost to ensure our politicians make all their decisions in the national interest, not in the interests of their own party donors.

A packet of crisps each. That's it. There may never have been as great a bargain as this.