Yammer, the San Francisco-based enterprise social networking platform, has announced its opening an office in East London’s Tech City area, next to London’s ‘Silicon Roundabout’.

UK Prime Minister David Cameron announced plans last November to transform East London into a major tech hub, one to rival Silicon Valley. And as we reported at the weekend, London’s startup scene is already thriving with shared working spaces such as TechHub helping to support fledgling tech firms – and this is the chosen venue for Yammer’s first European base.

London’s Silicon Roundabout area is already home to over 250 UK tech companies, including firms such as TweetDeck, Last.fm and Songkick. But part of Cameron’s vision was to attract companies from around the world, so with Yammer launching its European hub in the heart of Tech City, this is testament to the area’s status as one of Europe’s fastest growing technology hubs.

Yammer’s base at TechHub will facilitate 8 staff to begin with, and will provide a central sales and client service hub for the EMEA regions. Following its expansion, Yammer plans to double the number of staff in London by the end of the year.

The move to London was supported by London & Partners, the Mayor of London’s promotional agency and UK Trade & Investment (UKTI), the Government body responsible for encouraging UK trade overseas and foreign direct investment into the UK.

Mayor of London, Boris Johnson, said:

“Yammer’s decision to grow their business in London and at the centre of Tech City illustrates our increasingly pivotal role in the global digital economy. International firms are investing here because it is simply the best place in the world to do business and, with the international focus ahead of next year’s 2012 Games, we will be pushing hard to lure more and more of the biggest and best business to our great city.”

Yammer is like Facebook and Twitter, but for business. The network is based on users’ internet domain, which makes it ideal for companies to establish in-house social networks. Yammer has over 2 million users and more than 40% of Yammer’s traffic comes from users in the EMEA regions.

To date, Yammer has secured $40m in venture capital funding and more than 80% of Fortune 500 companies are customers.

David Sacks, CEO of Yammer, said:

“The opening of our first European office in Tech City is an important step for us as an organisation as we expand our reach globally. London was a natural choice for us thanks to its excellent links to the rest of the region and the high quality of talent in the area. The support of UKTI and London & Partners has really helped streamline the process and made the establishment of our office simple and easy.”

Yammer’s decision to set-up shop at TechHub is an interesting one, given that many of the companies there are young startups who either use the space to hot-desk and network, or those that are looking for an affordable alternative to a dedicated company office.

Mike Grafham, head of Yammer’s EMEA Customer Success Team, confirmed that TechHub could be a temporary measure whilst the company gets a ‘lay of the land’, meaning that a dedicated Yammer HQ in Tech City could be on the cards some time in the future. But with TechHub also expanding to new premises as we reported at the weekend, the possibility of remaining at TechHub remains an option.