The Jacobean design (aka Lord aka Milord) did not cease to be made in Czechoslovakia post 1934. There was a period of transition when a range of around 300 Jacobean items were on offer in the UK; some of them being "British Made" and some of Czech origin. Some moulds were in use for quite some time at Rudolfova Hut.
Selina, your tumbler does not look like the Inwald shape. A useful indicator, by the way, that can help to ID Inwald glass is to see if the base has a mirror shiny grind. There were other patterns that looked a bit like Jacobean; the block patterns are undoubtedly tricky.
Glen