I have one virtually identical, although mine has a discreet pontil scar rather than a depression - I see I've written 'wine c. 1820' on the foot.
We have to remember that historically booze was stronger in the C18 and early C19 than during later periods - although a can of Special Brew doesn't go amiss on occasions.
I've always thought the Brooks/Negus book useful and helpful in a general way - more so than many others - although perhaps you wouldn't use it as a first choice when assessing drinking glasses - but don't think I'd part with my copy.
There are more useful volumes for drinking glasses - Bikerton and Ward Lloyd are two of the best, although the late Ward Lloyd's volume is a little heavy toward the high spots - both however tend not to go beyond c. 1830, since it's Georgian glass that provides the investment area.
One book that will help greatly - and dirt cheap into the bargain - is E. Barrington Haynes paperback 'Glass Through The Ages'. A tad over-comprehensive perhaps but in view of the price mustn't be ignored - I seem to remember Anne (Mod.) saying that she'd paid something like £1. for her copy. Like many paperbacks, its down side is that the pages can become loose - they aren't bound and sewn into sections - instead they are bound in what is known as perfect binding I think - the separate pages are simply stuck with a rubberized cement into the cover.............. and as you'd expect not acid free paper, so some browning of the pages occurs after a while.
Coming back to Laird's glass - there is a reprint of part of an Apsley Pellatt price list (Fig. 10) - page 154 - in G. Bernard Hughes book 'English Glass for the Collector 1660 - 1860'. The final part of this image shows a variety of wine glasses, mostly with slice cutting, stemmed and with flat feet, and a variety of knop shapes. The glass shown here with a ball knop is one of the patterns on Pellatt's list - which is dated 1829 - so seems we're in the right area for date, give or take a little as is always the case with these things - but described as a wine rather than for gin.