I think it reached the point some time ago that it became reality that he wanted out and wanted a return to Derby from whom we signed him three years ago but Sean Dyche said he would decide when players would go and he's done that today after the East Midlands club made an offer in excess of £3 million for the 31-year-old central defender.
In breaking the news, Dyche said: "Jason really made it clear to me last year, and it's fair to say Derby County made an offer that was so large he found he couldn't refuse it.
"Outside the Premier League there are still some clubs throwing enormous amounts of money at the situation, and Derby are one of those clubs. His motivation was to go there for the contract that was on offer.
"We feel we had to stand as strong as we have done to make sure we got the required amount of money for him. That's got to a point today where he's been given permission to at least speak to them.
"It's highly unlikely that he won't leave. I think it's just dotting the i's sand crossing the t's."
Former manager Eddie Howe was keen to bring in Shackell in the summer of 2011 but he opted for a move from Barnsley to Derby with the Clarets then unsuccessfully chasing Stoke's Ryan Shotton who himself is now at Derby.
But Shackell was made available by Derby a year later and this time Howe got his man for a fee of around £1.1 million and immediately installed him as captain.
In three years he's missed just two games. They were early in his first season with us and were due to a back problem. Since, he's captained us to promotion, been one of the outstanding players in the team, winning the Clarets Mad Player of the Year for the last two seasons, and even popped up with four goals, one at his old club Derby and two, memorably, in the draw and win against Blackburn at Ewood.
It's been clear that he has wanted to leave for most of the close season, and Dyche has clearly been aware of that for considerably longer. When it reaches that stage then it is obviously best for both club and player that he leaves. It's a sad end though for a player who has been outstanding for us in those three years as a Claret.