I have no idea about the orange stamp, but can offer the following information about the others:
The S&H Stamp is Sperry & Hutchinson, Limited, so it is the UK version of the trading stamp. Here's an image of the book and address where they were once located (circa 1960s):

The National Letter Return Association was an interesting private organization that apparently
"sold stamps for the purpose of having certain mail matter forwarded to it upon arrival, from where it would be returned to the writers." Here's a post office decision about the firm dating back to 1885. Although I'm not quite sure what the benefit was to anyone who used their stamps, as the post office decision concludes,
"I see no reason why the Department should suppress this plan until it can itself afford the public a better one.":
