Rumours about Apple's upcoming iPhone 7 have suggested that not much is set to change, but leaked designs for the next model's cases suggest that there will be several significant differences.

The cases appear to show that Apple will get rid of the headphone jack, a move that could potentially result in a major backlash from customers who have splashed out on expensive headphones.

They also reveal a "dual camera" design, which could mean a vast upgrade to the iPhone camera making it capable of SLR-quality photos, as well as a "smart connector", which could be used to power accessories.

The 5.5-inch Plus Model, introduced in the iPhone 6 and continued with the iPhone 6s, has to date been largely similar to the 4.7-inch standard version. Minor differences include the addition of optical image stabilisation in the 6s Plus model.

But leaked photos of both handsets suggest the difference could be bigger this time round. Other leaked photos have suggested the smaller models will not have the smart connector, or dual-lens camera, although Apple is expected to remove the headphone jack on both.