This is Christine's 'pteridomania'

hope people won't object to my adding a pic or two of some similarly decorated pieces, and to Nigel's informative comments, and my own opinion would be to suggest that as a style this decoration appears to have also been not uncommon in a variety of places on the Continent of Europe - there appears to be a lot of thought that Bohemia was a probable starting area.
Silber & Fleming is awash with just about every type of table glass etc. showing fern engraving, and much of their glass was sourced from outside the U.K.
Interesting to see 'Walter's tumbler' in the attached pix, showing that ferny engraving looks to have continued well into the C20 (the date of his glass is 1932) - plus a bluebird

see also Neil's worthy contribution to this subject of fern decoration

....... "The obsession with ferns at that time was unbelievable and was primarily down to the fact that ferns have no male or female parts and therefore could be discussed by ladies without their having to faint in embarrassment. From that to Miley Cyrus in only 130 years!"