Thank you for downloading from the BBC.

The details of our complete range of podcasts and our terms of use,

go to BBCworldservice.com slash podcasts.

Hello and welcome to more all. broadcasts. the British mathematician Sir Andrew Wiles who's found a solution to a 300 year old mathematical

mystery and secured the prestigious Arwell Prize for his efforts.

But first, London has a newly elected mayor,

Sadeek Khan. In the aftermath of his election victory,

he named London the most diverse and fantastic city in the world. But is he right? Is it really the most diverse city?

Here's more or less his roving reporter Ed Davy. It's certainly a very diverse city. In the Dallas Hill area of North London, for example,

white British people account for just 14% of the population and of the 11 other ethnic groups

that make up the population there the largest is Indian at 11% so it's a real old mix-up.

The most recent count in 2014 found that 37% of Londoners were born outside of the UK.

Is that how you measure the diversity of a city, the percentage born in a different country?

Well, diversity is tricky to measure, so people have often looked at the proportion

born in a foreign country as an easy way to compare different cities, but it is a technique with

flaws. For a start, it doesn't catch second or third generation immigrants.

said Econ's election was meant to be a display of diversity but he was actually

born in London so he wouldn't count towards London's diversity measured this way.

Well I guess you could also obtain figures

for the total number of languages spoken in a given city or or the total number of

nationalities? There are problems there too though. In really big international cities, New York, Los Angeles or London say you could expect to find at least one person from every country in the world.

That wouldn't give a fair picture of the level of diversity on the streets.

...