Well in the case of this flask or vase it is certainly Holbein. Although Similar in style to Rembrandt with its portrait cartouche the body immediately tells us it isn’t. Rembrandt ware can be distinguished by its body and typically rough surface indentations, together with its heavier weight.
Yet, it is often harder to distinguish between Holbein and Kingswares as their style of decoration is similar, as it the body used for both. Originally the difference was in the price, the latter being cheaper to produce and indeed Holbein has been referred to as a more expensive product to Kingsware with added individual decoration.
This piece was a Charles Noke design as can be seen from his impresses signature.
Backstamps often help us identify Rembrandt and Holbein wares, however, these were often omitted for one reason or another, so today we must use our detective skills to distinguish between these wares!