Cheapest place for refills for Parker Jotter pens. I discovered that the refills in these Sigma pens fit my Parker Jotter pen. You get 12 pens for £5.99 - 50p each. Simply remove the refill from the Sigma pens and put it in your Parker. Much, much cheaper than buying Parker refills or even WH Smith own brand. Ebay listing ends on 27/1/17 and it shows there are more than 10 available at time of posting.
Seller is called jimbomoggins and they have 100% positive feedback.
This is my first posting of a deal so I hope I've done everything correctly.