By no means an expert on James Kent, but from the design I would date this to the 1950's - 1960's; some sites say "Old Foley" was used after 1955. Sadly the breakfast set is no where near as popular as it once was; for James Kent the most popular (and therefore the most valuable) pieces are those with all-over patterns - either Chintz or all over flower patterns like Rambler Rose or Chinese Rose. "Red Rose" would seem a good descriptive name. Yours is in very good condition which is excellent; if I was selling it, I would be asking $120 starting price and hope to go upwards. The Chintz and Rambler Rose sets seem to realise around $150-200 mark. Better manufacturers, particularly Royal Winton, are more eagerly collected, and therefore produce better prices, though still no-where near the heady Chintz days of 20 years ago. However "morning teas" go in and out of fashion, and it is a very pretty pattern. Good luck.
