I was in the media team at Gateshead when Mike joined as a player, and during his time as manager, and there was far more to him getting the job than just him being the oldest player. When he joined the club he joined as a player coach, it was a very, very, young team and he was the one real experienced player. So much happened in that season, with the club nearly going bankrupt and folding. Williamson was a real leader throughout, and helped out younger players who were struggling with tough times when no-one was getting paid. All experienced staff other than Williamson had gone by the end of the season, almost all players had gone. Williamson having been a coach, knowing the club, having a pull of being Mike Williamson a former Premier League player who has played in Europe and been Newcastle's player of the season in the Premier League one year made sense for all parties. He had a professional squad in the National League North, which is a bit of an advantage, but Gateshead are fan owned, don't own their stadium and rely largely on sponsors to survive. The budget was tiny and smaller than some part time teams. Despite that Williamson got his team playing some of the best football I've ever seen a side play. He's also been really good at improving players. Look at Macauley Langstaff's career before he started playing for Mike, he put his improvement down to the work Williamson did with him on the training ground. Then into the National League, with either the smallest or second smallest budget in the league Williamson got Gateshead to stay up last season while guiding them to the FA Trophy final. This season, still with one of the smallest budgets in the league, and Gateshead were flying high in the league when Williamson was poached by MK, and still playing great football the entire time. A number of out of favour players joined Gateshead on loan during this time, had the form of their lives and then earnt bigger contracts elsewhere. MK were 16th when Williamson was appointed. They are completely unrecognisable from the team he took over back in October.
I do think he would probably be reluctant to take on the job though unless he had assurances over contract length. He's got a young family, and I assume he's moved down to MK when he took the job - although I'm not certain about that. If they didn't, and if he was to move here then he'd be a very long way from his family up in Newcastle if they're still there. If they're not still there, and if they've gone with him then it could be difficult to persuade him to uproot his family again after such a short space of time.