This is a lovely Royal Doulton Lambeth salt-glazed stoneware vase in an Art Nouveau style, from around the turn of the 20th century. The design style, with its flowing lines and stylized motifs, is characteristic of the Art Nouveau or Arts & Crafts movement, which was prominent in Doulton's work at that time.
There are backstamps on the base which could provide a more precise date and identification. There are two artist initials: GS and LW (I think). The colors of this piece are exquisite, ranging from a deep blue luster finish to light blue incised leaves and an olive luster background with brown lines. Although it is not quite 7 inches tall, it makes a great impression.