Attention at all passengers. You can now book your train tickets on Uber and get 10% back in Uber credits to spend on your next train journey.

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Trains now on Uber. T's and sees apply check the Uber app. Hello I'm Simon Long the finance editor and this is Money Talks. Coming up this week,

what caused the latest flash crash?

There was an underlying theme for this, which explains why the pound ended up lower on the day

and indeed lower still since. And what's the best formula to win a Nobel Prize in economics?

Prizes that both look at a tangible microeconomic questions

and which also point out places in economics where markets don't work exactly as we might want them to.

So first in the early hours of Asian trading last Friday,

the pound saw a sudden unexpected plunge in value, a flash crash.

It had recovered most but not all of the loss by the following morning.

Computing systems, human error, and of course Brexit have all been blamed.

But what did cause the crash?

And if it was just a glitch, why did the pound not climb back to its pre-crash value?

I'm joined now by our Buttonwood columnist Philip Coggin.

Hello.

Philip, first of all, can we rule out human error?

What about computing systems?

Well, I don't think it was human error.

The pound was 2% lower in the course of the day which is a significant move on its own so if

it had been a fat finger trade it would have resumed its old level.

Computer systems almost certainly are involved because a lot of trading is done with

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