Here's a nice little find bought from eBay USA. This is from the Manchester Glass Bottle Works and marked "Woolfall Manchester" on the base. The Works was started circa 1833 by three men from Warrington, Thomas Percival (whose son ran Percival & Vickers), John Woolfall and William Jackson. Jackson left the business in 1840 and Percival died in 1850, after which John Woolfall carried on business for about 20 years, dating this bottle between 1850 and 1870. It is a 3 piece mould and the colour of the glass is very dark, virtually impenetrable towards the base. You can see a massive air bubble in the glass. I haven't seen any other pieces attributed to this bottle works.
I was a bit surprised that a bottle this early is marked but I am rather out of my depth with bottle glass. Does anyone know when bottles started to be stamped with the maker's name? 1860s, which this likely is, is quite early I would have thought. I would also be interested if anyone knew what it added to the glass to make it such a dark colour...