Blue lustre/lusterine pattern by Crown Devon Fieldings. 

The pattern is called Summer (pattern L52), which somewhat is similar to the patterns rural butterfly or fairyland. 

The tazza is decorated in butterflies with a gold trim and has a finished glaze of iridescent lustre on a blue background. It's in good condition.

On the base is marked: "Devon Lustrine, Fieldings, Stoke-on-Trent, Made in England, Summer".