well, I'll start the ball rolling for you Keith - although Jindrich or Pamela are obviously the experts you need. Oddly, the overall colouring is very untypical of pieces shown in Ruth Forsythe's book - in fact there is quite literally only one piece shown in her book with this darker background. However, as you already suspect, the style of surface decoration is very similar to a lot of Czech glass that was produced during the inter-war period - and I expect your assumption is possibly correct, with the piece having been made somewhere between 1920 and 1940, or perhaps a little later.
Reference: "Made in Czechoslovakia" - Ruth A. Forsythe - 1982 (Printed Ohio)