Final post for tonight
This is a lovely saucer, rather freely decorated in underglaze blue with overglaze red and gilt. Looking closely it seems it was extensively gilt, but almost all has rubbed off over the years. It has a hairline and some fritting, but it was a bargain so I couldn't resist
Again, not measured, but would estimate it's between 5-6 inches in diameter.
It's clearly an example of Chinese Imari, and I think I'm right in dating it to the Qianlong period.