Kralik is certainly a possibility.
As far as Christine's and Johns examples go, they are believed to be by Kralik. In the US we have a distinct advantage for ID which UK collectors generally do not have, and that is import marks. The examples shown above in the pics can be found in the US with an arched Czechoslovakia mark on them, which is a mark used by Kralik.
As far as Butler Brothers go...... Butler never identified the source of the art glass "assortments" offered in their catalogs. At least one of the Monographs published by the West Virgina Museum of Glass regarding Butler states in the preface that it is known that the assortments often shipped to the retailer in factory packed barrels, and as a result of that, the identification of a piece of glass in an assortment actually allows for the assortment to be attributed as to maker. Following that idea, I have actually spent a number of years working on Butler catalogs and the ID of assortments to see if it holds true for Czech imports. My process has been to match actual glass examples to the line art in Butlers ads. It turns out that the line art in Butler ads is actually reasonably accurate for the ID of glass items.
Here is a preview of some examples of match ups. The Butler images are reproduced from the West Virginia Museum of Glass Monographs with the express permission of the Museum. Eventually this information will be posted in detail on my website.
In the case of the last group, I have matched a basket with a unique decor to a Butler ad, and then matched more pieces in the same unique decor to show a partial decor family.
On a side note to the groups..... since they were shipped in factory barrels, and had to arrive in the US with country of origin stamps on each piece of glass, these groups and their packing and shipping methods also provide reasonably strong support for the belief that marks were applied by glass houses, and not by "exporters".
Hope this helps.
Craig