What is happening to my chard plants?

[YinMnBlue]

The leaves have developed pale papery patches.
Is there anything I can do to stop it and keep my micro-crop going?

Sunburn?

Eek, really? They are in a very sunny spot, and it has happened since I moved them from a less sunny spot

It looks like Leaf Miner, the larval stage of whatever pest laid it's eggs in the leaf. Have a look online to see the different ways of control.

Yes, I think you are right.
Thank you.