I've had this guitar a couple of years and for the last six months to a year it's just been in it's case. I've recently got it out to check it's all okay and what used to be the whitest white (dubbed 'pimp white') it's now taken on a cream/ yellow colour, but because it's a super gloss finish it doesn't look like a nice fade on a Fender, it looks tacky. Has anybody ever experienced this with glossy guitars, and is there any way to recover the old colour or am I stuck with this???

The photos aren't as great as they could be, I've tried to compare the whites with the paper pa next to it, the fade is uneven and the yellow is stronger in certain places compared to others. It's much worse than the photo shows...
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If the finish is nitrocellulose lacquer, you need to know that while this is a "traditional" finish, it will discolor, check, crack, chip. Has nothing to do with "gloss."

Nitrocellulose is a crap finish from the beginning of the last century that's made by nitrating cellulose (cotton or wood fiber, usually) in the prescence of sulfuric acid. It breaks down by outgassing nitric acid and sulfuric acid, which is where the yellow color comes from. The finish discolors and becomes embrittled, sometimes chalky. There are still those who consider this a benefit of the finish.