Could a 15-inch MacBook Air be coming as early as next month? Yes, if a report from Electric Pig is anything to go by.

The Pig is reporting that an "anonymous vendor" at a UK accessories expo held in London on Tuesday spilled the beans on the new size Air and said that it was part of a "shake-up [that] will happen in April".

While we'll reserve judgement on whether we think there will be a bigger MacBook Air landing as soon as next month, it is worth noting that this isn't the first time we've heard murmurs of a 15-inch skinny Mac.

In July 2011, sources, as sources are want to do, told MacRumors that Apple was already working on a 15-inch super-skinny MacBook Pro. At the same time TUAW reported that Apple was also looking at releasing a 17-inch version, thereby covering all screen sizes.

Then, in November that year, Digitimes sources hinted at new 11, 13 and 15-inch versions of the MacBook Air and Slashgear reported that the new Air could make use of Intel's new Ivy Bridge processors.

Apple doesn't have a traditional launch month for its svelte laptops. The original MacBook Air landed in January 2008, followed by a refresh later that year. In mid-2009 the third generation landed and it was more than a year later, in October 2010, that we were treated to the new super-skinny design - a design that was once again revamped in July 2011.

So, while it's likely that a new MacBook Air range will land sometime in 2012, what month, what sizes and what this means for the MacBook Pro range remain to be seen.

Watch this space...