Terry
It's clean-out day on Thursday, I'll add the vinegar and water to my list of cleaning tasks. Thanks for the tip.
And yes, BirdieWife, Betty has got her corner of the hen run - the space behind the henhouse and now I've put my chicken watching chair in front of it it makes a safe corridor for her to extend her range down one side of the run.
She seems quite a friendly bird and seems quite resigned to her fate at the moment, she keeps creeping round the far side of the hen house where the others are and if there's enough distraction (ie me with food) she can get quite close to them without any trouble then they spot her and she's chased back in her corner again.
I was worried that there was no shade in that corner so I've put the big carry box there to give her some shade.

One thing that has surprised me is how much they drink. Because they've got a very big water hopper I've not been able to calculate it, but I've given Betty an emergency supply of water in a cup which fits on the weldmesh. This is about the size of a teacup and she gets through two of these a day with supplementary topups when she can sneak to the main water thingy.

Sue