Fantastic Paul. Well done! Many thanks for taking the time
I've done a little search for J.W. Sutcliffe & Co. (established 1898) and they are shown here in "History of Glass Making in London"
http://www.glassmaking-in-london.co.uk/WorkingPremadeGlass - scroll down to no.134 (dated 1950). It appears they made domestic glassware, e.g. fruit preserving jars, glass containers, metal and plastic closures for glass containers. They also are featured in National Trust Collections for jam jar lids. I've looked in my Miller's "Bottles & Pot Lids" collector's guide, but they don't feature, perhaps not surprisingly
The bottle and stopper (mustn't call it a decanter
) is made in a two part mould, running diagonally from one corner to the other.
I just wonder if the image is shown deliberatively dark so that the pattern can be seen better? I can't imagine bath salts or bubble bath being put in a coloured glass bottle, as these are usually quite colourful and you wouldn't see the contents
The thing about bath salts containers etc. is that they look really pretty, and I wouldn't mind betting this bottle had a ribbon and bow around it at one time.
I'm not sure what I'll use it for if at all. I was just intrigued by the reg.no. It will probably go back to the charity shop