Finnish handset vendor Nokia launched a suite of new smartphones at its London Nokia World event on Tuesday, amid the boardroom turmoil that has seen departure announcements for its two most senior executives within days of one another.

The firm unveiled a trio of high end devices built on the new version of the Symbian platform, Symbian ^3, which together with the flagship N8 will form the first wave of Nokia’s renewed assault on the smartphone sector. The E7 is the new offering for the corporate sector, the C7 is pitched at social network users while the C6 is a scaled down unit aimed at users who want less bulk.

“Today our fight back to smartphone leadership shifts into high gear,” said Niklas Savander, executive vice president, Markets, Nokia. “Despite new competition, Symbian remains the most widely used smartphone platform in the world.  Our new family of smartphones introduced today feature the all-new Symbian OS, rewritten to be faster, easier to use, more efficient and more developer friendly.” Savander also gave a nod to the N8. “Based on the level of consumer interest and the highest online pre-orders in Nokia history, we expect big things from the Nokia N8,” he said.

The E7 could be seen as the heir to Nokia’s Communicator series, with  a slide out QWERTY keyboard, 4-inch touchscreen display and Microsoft Exchange ActiveSync. The C7 sports a 3.5-inch AMOLED display and majors on Facebooka dn Twitter integration as well as Yahoo! and Gmail account information on the homescreen.

Much has been made of the pressure Nokia finds itself under in the high end, with Android handsets gaining popularity and the bespoke players like RIM and Apple gaining serious ground. But Jeremy Copp, European VP for mobile at industry research firm ComScore and a former Symbian employee, suggested there are reasons for cautious confidence.

“Nokia is still dominant in the rapidly growing European smartphone market with 51% market share; its share has decreased 14% while the market has grown 41% since July 2009 to over 60 million smartphone users,” he said. “Nokia will keep innovating and will keep bringing out great devices for a wide variety of audiences. Certainly, Nokia’s future will not be predicated on the success of one device,” he said