Question about latest acquisition ?

I've just got two of these for £6.03 delivered - they're not the best condition but the most of the design is there.
https://en.numista.com/catalogue/pieces28173.html?mobile=0
Question is why the 4 ? Ha !

From wikipedia
The "Sign of Four"[12] was an outgrowth of an early Christian symbol, Chi Rho (XP), standing for Christus Rex in Greek letters; this was simplified to a reversed "4" in Medieval times.
http://en.wikipedia.org/wiki/Merchant's_mark

Hmm very interesting ! I love some of the old EiC coinage