Hello, I'm Maeve McClenigan and this is the tip-off.

I'm an investigative journalist and here in the UK we have a long and proud history

of digging deep and exposing wrongdoing.

On this podcast, I'm going to be talking to some of the UK's best investigative journalists

to hear the stories behind the headlines.

This week on the tip-off, wigs, car chases,

and bags stuffed with cash. This is the story of how journalists exposed the questionable practices of the Conservative Party's largest donor. My name is Heidi Blake and I'm the UK investigations editor at BuzzFeed News.

Back in 2015, Heidi Blake had just set up a new investigations team at BuzzFeed UK and was on

the hunt for a story. One evening, she was in a pub in central London when a tantalising piece of

information came to light. So I was drinking a pint of Guinness in a pub in central London when a tantalising piece of information came to light.

So I was drinking a pint of Guinness in a pub somewhere around King's Cross

with a source that I'd known for a while, somebody I had reason to trust.

And we were chatting about an entirely separate matter and this person just kind of casually

mentioned oh hey by the way would you be interested if I were to tell you that the single biggest

donor to the Conservative Party looks like it's laundering money through the post office and I was

like like yes I'm interested please you tell me what you know.

The name of the company in question rang a bell, but it was hardly well known, like a mobile.

So they're actually a really big company. They're telling over a billion pounds a year and more.

But they're actually sort of relatively little known outside the community that

buys their airtime. Once you start looking at them, you realise that their signage is on basically

like every newsagent in the capital and across the country and actually across Europe when you

travel. But they kind of somehow managed to say reasonably out of the public consciousness.

...