I like to read old, rare garden and farming books and came across the following recommendations for fertilizing in quite a few UK publications.

One frequently mentioned product was:
CLAY'S FERTILIZER

I found a poster that can be purchased that at least shows the product but doesn't say what it was exactly. And even though it says 'manure' on the poster it seems that the term 'manure' was used not only for manure but also as a general term for what we call today fertilizers. For instance in old books they will also call superphosphates 'manure'.

http://www.vintageadvertisingprints.co.uk/product_info.php?products_id=93

Believe me I have searched on the internet and looked up all the references but can't find anything other than its name. Does anyone know what components made up Clay's Fertilizer?

ICHTHEMIC GUANO is another fertilizer. I don't know what ichthemic means or where this guano came from. Other guanos are referenced but not as frequently as ichthemic.
Googling a definition for 'ichthemic' doesn't help.

THOMPSON'S MANURE is the last one. One time it was called Thompson's Chrysanthemum Manure.

Any help would be much appreciated though I understand if these are long forgotten recommendations.

Just found a circa 1915 N-P-K breakdown of all the fertilzers available in that year done by New York Commission of Agric.

All 3 fertilizers were listed and obviously sold in America too. Now I know a bit more about them.

thanks for the tip about the fish connection from the word
'ich'

I actually was mistakingly thinking it meant bird related but that would be 'orn' as in ornithology.