This is a Royal Winton English dish made by Grimwades Limited.
The base of the dish itself is square-shaped while the edges of the dish are rounded, with two sides opposite one another featuring a rolling arch design extending outward. The edges of the dish are decorated with a violet ring going completely around the plate. Within the dish are two main arrangements of red, purple, yellow and pink painted flowers - one arrangement sees the flowers growing towards the center of the dish, whereas the other shows the flowers growing towards the edges to the side. On the two arch sides are two smaller flower patches each.
Grimwades Limited is a Stoke-on-Trent based company founded by the brothers Leonard Lumsden Grimwade and Sidney Richard Grimwade. The company began in 1885, producing dishware, earthenware and bone china. The company would later become more renown for its Chintzware pottery designs in 1928. In the 1980's, the Coloroll conglomerate would acquire the company. However once Coloroll was undergoing financial failure, the Royal Winton rights were bought by management and merged with Longton's own Duchess China Limited. Given the dish's style and the fact that both the Royal Winton and Grimwades names are printed, this dish is presumed to be from the late 19th/early 20th century.