Pardew was in charge of Newcastle from 2010 to 2014.
The team enjoyed success during most of his tenure as manager.
The high point of Pardew's time at the club came in 2011/2012, when he fired them to fifth place in the Premier League and a Europa League quarter-final appearance.
Pardew won the LMA Manager of the Year award after the 2011/2012 campaign, and signed an eight-year extension at the club. But he chose to leave the club two years later due to fan pressure, after a series of poor results.
In an exclusive interview with Tribalfootball, former Magpies centre-back Williamson spoke about Pardew's impact at Newcastle and his eventual departure.
Williamson, now player-manager of Gateshead, said: "To be brutally honest with Alan Pardew, I probably didn't really respect him to the extent that he deserved until he left.
"I did respect him, don't get me wrong, like I could really see how strong minded a character he was, but it wasn't only really after he left that I saw the effects that he had and how much he achieved at the club, so he was a fantastic manager and he really did deserve all the credit he got.
"In terms of him being out of a job at the minute, I would presume its more of a personal decision more than him not being able to get a job.
"I don't know his family situation and circumstances but I think being in management for the amount of years he has maybe he is just enjoying a little break and some freedom because it is really intense."