You do not need to be to fussy about the thread you use, as long as all the threads are roughly of an even thickness and the same fabric, usually wool, throughout one tapestry.
I have inherited lots of tapestry wool, all different makes and thicknesses, some stranded and also bought job lots at auctions. I mix all makes and brands together. Stranded wools can be separated and regouped into twos, three or fours.
No one looking at a a piece could tell that I had used different brands of wool to make it.
Good Morning Tuesday 23rd April St Georges Day
To think that London, or anywhere else for that matter, does not belong to any one demographic