Joanna Shields,the vice president and managing director of Facebook’s Europe, Middle East and Africa operations, is leaving to become the chief executive of the Tech City Investment Organisation

Another post-IPO executive departure for Facebook, this time on the international front. Joanna Shields,the vice president and managing director of Facebook’s Europe, Middle East and Africa operations, is leaving to become the chief executive of the Tech City Investment Organisation. And in a (possibly temporary) step up for another exec, Facebook tells us that Shields’ reports will now report to Carolyn Everson, the global VP of marketing for Facebook.

Tech City is a David Cameron/Conservative government initiative to develop a technology hub in the East End of London to rival that of Silicon Valley and other major tech centers.

It looks like for now Carolyn Everson’s assumption of Shields’ reports may just be an interim measure, but it also could be a sign of her growing position at the company. Indeed, as Facebook continues to position itself for more revenue-generating activities, in some respects, the marketing relationships that fall under Everson’s (and formerly Shields’) remit are perhaps the ones that Facebook can least afford to let drop while it weathers churn at the management level.

The news of Shields’ new job was first reported by the Telegraph (a Tory-backing newspaper) earlier tonight.

Shields, an American ex-pat, is coming into a role that has been up for grabs since June, when chief executive Eric van der Kleij said he was stepping down to serve as an advisor to the Canary Wharf Group, a real estate development company that wants to bring more tech companies to the Docklands area of the city, which is currently very heavy on investment banks and other financial industry businesses.

Tech City has had its ups and downs since first being established in 2011. Started with some fanfare by Cameron as a route to revitalizing the East End of London by catalysing some of the tech startup activity that was already happening there, critics asked why the government chose to focus on one part of London when there are tech companies spread out to many other parts of England, such as Cambridge for hardware. Some have accused Tech City of being little more than a PR machine.

Whether Joanna Shields will be able to turn that image around will be the big question. The TCIO has already said that it plans to split the job into two, with the CEO having an external facing role and a deputy CEO acting as more of an event organizer.

Shields is already looking to take the Tech City vision into something beyond just London. “The spotlight has been thrown on the east London cluster,” Shields told the Telegraph in an interview. “We have to give this Government credit for recognising the success of it and then reacting with policies that are absolutely spot on for incubating businesses, not just in the cluster, but all across the UK.”

To be fair, there have been some very notable advances in London-as-tech-hub: among them, Google establishing its multi-story Campus incubator and events space; Amazon and Facebook both building out their operations in the city; General Assembly arriving in town; hundreds of startups in between all of that; and even an exit (the first, apparently).

Some of that is also just a consequence of how the tech world has continued to grow and globalize. We’ve also seen huge developments in Dublin, Berlin, across Israel, in Russia and more. Is London extra-remarkable in that context?

Before coming to Facebook, Shields had already established her tech credentials at the executive level: she had previously been the CEO of social network Bebo and also worked as a senior executive for Google in Europe, among other roles. This is her first foray into public policy.

Shields’ departure from Facebook follows a string of other executives leaving after Facebook’s IPO. Among them have been CTO Bret Taylor, Platform head Carl Sjogreen,and Ari Steinberg (influential engineer who had most recently been leading FB’s Seattle office). Three other recent business exec departures include head of partnerships Ethan Beard, director of platform marketing Katie Mitic, and platform marketing manager Jonathan Matus.

We have reached out to Facebook to find out who will replace Shields and will update this post as we learn more.

Update: Facebook has sent us the following statement:

Joanna has been a tremendous contributor to our EMEA organization and her leadership and passion will be missed. Facebook supports the UK Government’s vision for building a stronger technology-based economy and start-up ecosystem, and we wish Joanna every success as she moves into her new role at the Tech City Investment Organisation and as the Business Ambassador for Digital Industries.