Samsung will put the rumours and alleged leaks about its next flagship smartphone to rest when it unveils the handset in London later on Thursday.

More than 20 million copies of the existing Galaxy S2 have been sold since its launch in April 2011.

Analysts say its success helped Samsung overtake Nokia to become the world’s best-selling mobile phone maker.

Changes in screen size, form factor and a higher-resolution camera are among changes that may drive its appeal.

Battery life
Samsung has been close lipped ahead of the event, refusing even to confirm the device’s name – its website only states that its is “the next Galaxy”.

It has, however, said the phone will not include a 3D display, but will be the first device to feature its new Exynos 4 quad-core chip.

It promised the Arm-based design would offer double the processing capability while using 20% less energy than the chip used in the S2. It can also record and playback video in 1080p high definition resolution.

But many company watchers believe the presentation will concentrate on what the device is like to use rather than raw statistics.

“To the normal consumer the chip is not important per se, but the experience it offers is,” said Carolina Milanesi, research vice president at the tech analysis firm Gartner.

“So less battery use, better touch response and the ability to better handle multitasking to let more operations be carried out simultaneously will all be noted.”

Smartphone shoppers can be very fickle. Blackberry-maker Research In Motion and HTC have both seen sales lag after misjudging the appeal of their high-end devices to consumers.

But Gavin Byrne, principal analyst at telecoms experts CCS Insight believes Samsung should avoid the same pitfall.

“There are only two big companies in the smartphone market making sizeable volumes of profit at the moment – Samsung and Apple,” he said.

“Samsung is now a long way ahead of its Android-based rival HTC after the Taiwanese firm had misses with some of its launches.

“Samsung on the other hand has finally learned the lesson that software and making its devices desirable in themselves counts, rather than just having the best technology and specifications.”

Special event
The level of speculation surrounding the phone suggests Samsung’s decision to hold a special event, rather than launch the handset at Barcelona’s Mobile World Congress, is already paying off.

But that also increases the risk of a backlash if the upgrade is not seen as a major step forward.

“Events such as this are incredibly important as it gives the company a world stage to launch their product,” said Stuart Miles, founder of the tech site Pocket-lint.

“I’m a great believer that trade shows are good for trade but not launches, as a company only has an hour until a rival’s product comes along competing for attention.

“It’s all about positioning and timing – if you don’t get it right the fire isn’t lit and the product won’t carry forward.”

Samsung will reveal details of the device at 7pm BST at London’s Earls Court Exhibition Centre.