[coco]

Can you please offer any advise?

This is an older lady, she lives with five others.  No scaley legs or anything but comb has gradually gone white, it looks like a white bloom, notice today it looks like it is also on her bottom eye lid although I've not had a poke at it.

She is healthy and seems totally unaffected, none of the others have this.

A look online offers all sorts of theories from worms to yeast infection, so thought I'd would check with you guys first.

[grinling]

has their feed been wet?

[coco]

Yes we've had so much rain here that there has been a lot of mud.
Half of their enclosure is concrete but the other half is soil.
I've read somewhere thst athletes foot treatment can work, wondering if it's worth trying some of that?

[coco]

Sorry read that as feet  just realised you said feed ... but yes it probably has been wet. It's put out fresh every morning, keep it in the house so  it's clean/dry,  but would of got rained on if it was raining.

[New shoot]

It does like a fungal infection, but I'm not sure.  They can be linked to a depressed immune system, due to age or other factors.

If it is ringworm, that can spread to the other birds.  If it a fungal infection, it needs diagnosis to get the appropriate treatment for it and check for underlying causes.  Either way, I'd say she needs to see the vet. I wouldn't use a human treatment on her.  Apart from the fact that it is not licensed for that use, you would have no idea what effect it would have - good, bad or even dangerous to her 

[grinling]

I would also rec seeing a vet as it could be favus. Check that whatever med is prescribed the egg withdrawl time.

[jaydig]

When we had the really cold snap a few weeks ago, one of mine decided to sleep on the chicken house roof instead of inside in the warm, and the top edge of her comb when almost black, I suspected from a touch of frost bite.  It gradually went paler until it looked exactly like your chook's comb, but now, finally, it is returning to the proper red colour.  This might be totally disconnected from the problem you have, but maybe it's a possibility?