Can’t try that in Britain. We’ve already had our allocation of sunshine until next May.There's a potential solution nobody tried, it's keep your toys in sunlight for a few hours, I've done it with Earthrise Megatron and Buzzworthy Dinobot and seen a little improvement.
Anyway, NGL, I’ve been following the premature yellowing thread over on TFW, and it’s stopped my purchasing of new stuff in its tracks. Haven’t bought as few TF items in year going back to 1995. I’ve only had a few of the usual suspect premature-yellowers affected, but it’s enough to keep me very wary. (I mean, I’ve got TF figures from Earthrise and onwards which have discoloured worse than some of my remaining old G1 stuff.)