WHEN the Dundee United team bus pulls up at Parkhead on Saturday, Mark Wilson will be back at the ground he thought he would never leave.

It is not uncommon for someone playing in a cup final to experience a shudder when he first sets eyes on the stadium, but Wilson is more likely to suffer a tug at the heart than nerves. Dundee United's defender is preparing to take on St Johnstone at the ground where he spent the best six years of his career.

He won four league titles, two League Cups and, in 2011, the Scottish Cup as a Celtic player. The 29-year-old is about as level-headed and professional as any manager could want, but he began to feel like he was part of the furniture. Eventually he allowed his thoughts to stray to spending the rest of his career at the club he had supported as a kid.

Neil Lennon's decision to let him go was not easy for either of them. "Leaving Celtic was quite a hard thing, mentally," said Wilson. "For me, being from five minutes from the ground and being a supporter all my life, then getting the opportunity to play for them and play for them for so long, perhaps I took it for granted a wee bit."

The writing was on the wall when Celtic signed Adam Matthews and Mikael Lustig, two right-backs. Wilson asked Lennon for clarity about his own position in January, 2012. When Lennon said "we'll see what happens" Wilson knew his days were numbered.

"When you get told your time's up it's very difficult to get over that. It was the right time for me to go, the right decision from the manager, I've no complaints," said the United full-back. "It was just about getting over not being at a club of that size, that magnitude, and everything that comes with it. You're treated like a king there. You don't need to do anything, there are people doing everything for you.

"When you've been there for six years it's hard to get used to going to another club, like Bristol City which was a poorly run club compared to Celtic. It's not grieving, it's a game of football, but if you're comfortable in a certain position at a job for so many years then you get in a comfort zone and that's the way I was. It's been a breath of fresh air coming to United, for me, and getting to a cup final."

After an unhappy, brief spell at Bristol he returned to United, his only club before Celtic.

Wilson has been down the cup final route before. He was in the United team which lost the 2005 final to Celtic, and then in the 2011 Celtic team which beat Motherwell, both at Hampden. For him, the outcome was different and so was the entire experience, even before a ball was kicked.

"The expectation at Celtic is that you're going to win it," said Wilson. "Going into a cup final with Celtic everything is geared to you winning it, you're just expected to win it. Things like the after-party are all booked, it's all planned. I played in the 2005 cup final with Dundee United and it's a lot of ifs, buts and maybes.

"That's the difference for smaller clubs, it'll be the same for St Johnstone, it's a massive occasion. A Scottish Cup final for Celtic is a big occasion but it's not quite the same. A lot of players in our side, and I'm sure St Johnstone will be the same, will never have played in a final. So for these guys it's the best moment of their career.

"There has been so much said and written about the young United boys this season and it's fitting they have reached a cup final to showcase their talents. I hope they take it all in, because cup finals might not come around too often for United."