would you like to post names and y.o.b. and which census you are having difficulty reading???
Maybe we can help
There is a William Blackwell c.1825 living Shepshed and later Loughborough -his occupation was Frame Work Knitter - usually written as F.W.K. and sometimes Cotton, wool or silk follows this -depending on what kind of yarn they used-sometimes it will state cotton hose/silk hose -mainly it just states F.W.K. Could this be your P.N.K.

You can look up free on FreeBMD for registrations from Sept qtr 1837 - usually you can work out the correct person from p.o.b.
Pre 1837 you have to look in parish records
The IGI -free at familysearch is useful for baptism dates -trustworthy are the extracted records - treat "member submitted" records with caution.
Unfortunately you need to purchase "key " certificates for full information (£7 from G.R.O.) or visit the records offices
Why not post exactly what you are looking for on here -names, dates, etc- someone may have the answer -or at least be able to tell you where certificates ar e necessary (always a good idea if you can purchase some )
What do you mean by "one firm looks like St P.N.K. (Cotton)" ?
If If this is a from a census form, census do not usually (1841-1901) give the name of the "firm" -just the occupation and then whether "worker" or "employer"
Suz