discoloured wool

not sure where to put this so this will do.

I bought a white knitted merino wool set for baby to wear home from the hospital and hand washed it yesterday in a tiny bit of wool wash liquid, and layed it flat to dry in the shade (it was also an overcast day) and it has yellowed is there anything I can go to whiten it again?

Pleeease help! Thanks

I asked Mum - she says that sadly she hasn't found a way to help once they're already discoloured . She did say that some wool is really prone to it, and you can hardly prevent it happening in those cases.

But you never know, perhaps someone on here will know about a trick she hasn't heard of?

And I have a vauge recollection in the back of my mind about lemon juice... but I'm sure Mum would have known about that if it was helpful.

I (or rather my MIL) managed to discolour some white knitted matinee jackets by hanging them into the sun to dry.. I tried vinegar soaks, napisan, mild bleach (all things I read on line). The vinegar possibly lightened the yellow, but nothing removed it. Don't use bleach - on one of the jackets it has seemed to have hardened the wool a little.

And, despite telling her about the discolouring and the reason why (although I didn't tell her she was the one who hung them out in the sun) she did the same to my DS's last white matinee jacket last week. SO disappointed because people had gone to so much effort to make them for us.