London (CNN) – British Prime Minister David Cameron has made no secret of the spoils he hopes that hosting the Olympics will bring to London - and the UK.

The estimated $20 billion of investment over the next four years would offset some of the $14.5 billion splurge of staging the Games.

Last week he helped launch a $1.6 billion investment drive to drum up business for UK plc.

Lancaster House in central London has been made into the British Business Embassy for the duration of London 2012. Organizers expect more than 4,000 of the world’s top business leaders to attend a series of summits.

Alongside this home-team charm offensive, delegations from around the world see a golden opportunity to promote themselves. All across London, various nations have taken over landmark locations to showcase culture and cuisine, and offer a home away from home for athletes and fans.

There is also fierce competition for the attention of the business world. From official sponsors to representatives of every size of firm in town, the Games have transformed London into a giant trade fair.

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Russia, host of the winter Games, has set up in Hyde Park, while the German House will be based in the Museum of London Docklands, and on a five-star cruise liner, MS Deutschland is in nearby West India Docks. Ireland has a more modest set-up in a pub beside Kings Cross Station, and African nations have pooled resources to share Kensington Roof Gardens.

The Netherlands have linked up with Heineken, billing themselves as party central at Alexandra Palace, while Denmark has moored its replica Viking ship at St Katherine’s Dock.

In short, there is barely a part of London that has not been colonized by individual nation states.

Scotland House has a track record of using international sports events to attract investment. According to First Minister Alex Salmond: “You have to be quite frank, this embassy is about commerce and investment."

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He added “I have spoken to five people this morning who I had been looking to speak to, I could have gone to them or they could have come to Scotland, but in the event both of us have come to the Olympics and it works well for us both.

"Will people decide to invest in Scotland because they had a meeting with the First Minister at the Olympics? No, but then we don't just offer that.”

While we found that Imagine Denmark was crammed with Danes and Swiss House with mainly Swiss, tourism does play a part.

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Bagpipes and music from Scots icons The Proclaimers were at the launch of Scotland House, a climbing wall with demonstrators in mountain-gear greets visitors to Swiss House and a Hans Christian Anderson kids entertainer is performing at Imagine Denmark, alongside piles of Lego, naturally.

Behind the scenes these national houses run networking sessions and facilitate meetings to push their business agenda.

According to Nicolas Bideau, Head of Presence at Swiss House:  “In Beijing the job was easy because at that time the relationship was booming between China and Switzerland and the Chinese were fascinated by Switzerland, it was easy to catch citizens and business-people. "

He adds: "Here is London it is not the same. UK people know Switzerland, they are not as fascinated as the Chinese were. We have got to be competitive.”

They’ve done that by displaying iconic brands, like Lindt chocolates and Victorinox.

Casa Brazil is one of the biggest hospitality operations, because after London 2012 it is all eyes on Rio 2016. But even those without an Olympic hosting remit see the chance to network and sell their wares.

The Olympics is of course about flag waving and winning medals, but for business, the ultimate goal is bringing home the bacon - building firm foundations for trade.