I've passed this numerous times over the years when walking my dogs and wondered what it was all about. Recently I decided to research it on the internet so typed it into Google (other internet search engines are available) and discovered I'm not the only person wanting to know about it.
Apparently it's artificial granite made by mixing granite chippings with a slow setting Portland Cement to produce all manner of cast items. It was made at a place called Croft in Leicester by a company called "Croft Adamant". The year 1905 is probably the year it was either made or layed?
I hope you find all this of interest and I'm nominating this Blog entry in the category of "Most Boring Item on the Web 2014" at this years' Internet Awards. :)