I think the seller may be telling a porky calling them NOS - with the exception of a couple of items they look distinctly used to me.
There are some quality items there for their day - MK and Crabtree from the 1970s/80s. Some of the socket outlets towards the top left of the pic, and one towards bottom right, look like much lower quality MK imitations from the late 90s. They're between 20 and 50 years old, and for the most part I don't believe that they are new old stock.
However good or authentic or whatever they may be for your aesthetics, I don't believe it's wise to put any of those back into service - you don't know what sort of usage they've had, what condition the internals are in, or how much load has been put on them in the past that could have led to deterioration of the electrical contacts. If you're employing someone to wire this place up for you, there's also the strong possibility that they might refuse to install them due to the possible implications in terms of liability. I wouldn't do it.
I know there's an imperative to reuse, recycle etc these days but with electricity, safety has to take precedence. There is a wide range of styles available new, and you're sure to find something that goes with the look you're trying to create. Have a look on Screwfix, ToolStation or TLC.