Hi Mark
Here are a few links.
Red-legged Partridge
http://www.blueskybirds.co.uk/rlpart.php
Quail
http://www.flpa-images.co.uk/bin/flp...common%20quail
I have checked and there have been two reports of singing Quail this year so far, and both in Lincs. One on the 5th April & one yesterday so perhaps you did see Quail after all.
If you are certain about it then I apologise for doubting you. I feel that if your perception of the bird was smaller than a Grey Partridge then it is likely to be a Quail. If so congrats on a super find. I have only ever seen one in this country and one abroad. I have heard plenty but they are one of the most difficult birds to see. Very good at throwing their voices.
John