Cities dominate the UK. Both Manchester and Leeds have economies of over £50bn, which makes them more productive than the entirety of Wales.

However, the rest of the country is somewhat outgunned by London's size and scale. It accounts for roughly one-fifth of jobs and businesses and one-quarter of the UK's economic output.

London's sheer dominance has led some, including business secretary Vince Cable, to call the capital a drain on the rest of the country. The new Cities Outlook report by the Centre for Cities compiled various data sources to discover whether this is true.

Migration to London - is there a brain drain?



One of the factors when looking at how London affects other cities is to establish what exactly it takes away. According to the report, it seems that one of the big losses could be young talent.

The theory behind a brain drain is that if one city is attracting all the talented graduates then other places are missing out on those skills.

Overall, London loses people to the rest of the country with 933,000 people moving elsewhere each year - equivalent to the entire populations of Nottingham and Bolton combined - and 775,000 moving into the capital.

However, almost one-in-three of the 20- to 30-year-olds that decided to relocate between 2009 and 2012 moved to London. People tend to leave when they are aged 30 and over. The report also analysed student migration flows into large cities. The conclusion was that these cities were attracting students but losing them to London once they had graduated.

London's presence in other cities



While you might think London restricts the development of other urban areas, data suggests its growth actually creates employment elsewhere.

London businesses are the most successful at expanding into new cities. This is particularly true in Crawley and York, where one-in-five private sector employees works for a business with London headquarters. However, businesses that open in other cities are less successful at moving elsewhere in the country.

Leeds generates the highest number of jobs in 20 cities if London is discounted. Businesses from other cities are also much less likely to create jobs in London. Edinburgh has made the biggest impact in the capital, but this amounts to just 1.1% of all private sector jobs.

Innovative cities: who gets the most patents?



Ideas and inventions are important for economic growth, so it may surprise you that London was actually ranked 23rd when it comes to the number of patents granted in cities when adjusted for population.

Cambridge came out on top for finding new ways to make goods or deliver services. With 68.7 patents granted per 100,000 people, it had more than the next five most innovative cities combined.

In Swindon and Edinburgh, more than 50% of patents originated from one single firm. With the exception of Bristol, the report shows most creative cities are in fact small.

So is London a drain on the rest of the UK?



The conclusion that the report came to is that London's success generates a lot of economic opportunity, especially internationally. Also, in reality the UK's "next largest cities punch below their weight", with only Bristol performing better than the national average on the range of indicators in the graph below.

It adds:



This is in line with previous work that has showed that England's large cities are much smaller than large cities in other countries and tend to perform less well than their European counterparts.

Similar to the questions around Britain's relationship with EU, it is tough to put your finger on what other cities would lose if London was constrained. However, it seems clear that London may take but it also gives back too.