Hi Emma - not so sure that these extra pix really do help - and although I'm usually in awe of Lustrousstone's knowledge of glass, my own opinion is that clear glass such as this needs a uniform dark background

I'd agree that this bowl shows a 'pan-top' (shallow saucer shape) - certainly found during the early part of the C18, and seems to have predominated in the middle third of the century, often on sweetmeat/syllabub glasses - the reason given is that it facilited the use of a spoon to remove the contents from the glass. However, apparently Sam. Pepys also mentions syllabubs in the 1660's, so maybe the shape is much older.
According to the books champagne glasses also were sometimes made with a pan-top, so obviously a popular shape.
I'd agree with Lustrousstone that the decoration - which incidentally is wheel engraving, and not etching (acid process) - does look to be C20.
Feet of drinking glasses can provide much information which often helps to date - although you don't provide information about the underside of the foot - does this have a snapped pontil scar - a smooth depression where the scar was removed - or perhaps simply a flat underside. What is the colour of the piece, are there seeds etc., and does the glass have a good lead glass ring when flicked.
What in particular made you suggest the C18 ?? With such pieces it's improbable that you'd find a maker, or even a country of origin mostly, but nice glass by the way, and deserves to hold some champagne
