Is this plate chinese ?

by alison
(cumbria , england )

Hi , i found this plate when clearing out my late dads house . (he had loads of very old plates that belonged to his mum , her mum ( his grandma ) and her mum (his great grandma ) . I cant find out anything about the maker chensi . It also has t something s on it and the letter B indented on it and another mark . please help is this chinese ? how old about is it ?, and is it a keep or just rubbish ? . Its approx 7" round . I would love some help .thanks