Essendon called a press conference this afternoon to announce what had been heavily speculated for six weeks: that Mark Thompson would be joining the club's coaching panel as a senior assistant alongside rookie coach James Hird in 2011.

The former Geelong dual premiership coach turned up unannounced at Essendon training today, walked on to the oval and spoke directly to Hird and told him of his decision. Hird then relayed the news to the playing group midway through the session.

But neither Hird nor Thompson nor president David Evans were present at the media conference; the announcement that Thompson would come on board was made by football operations manager Paul Hamilton on his own.

Hamilton was forced to answer questions about the methods used by Essendon to lure Thompson from his contract at Geelong - he had a year to run on his four-year deal - which had drawn criticism from some quarters and certainly raised the ire of Cats' officials.

''At the end of the 2010 season, this club made a decision to assemble the best football department we possibly could,'' Hamilton said. ''But we can't comment on the individual process of getting Mark to the club.''

Hamilton said it was a memorable day for the Bombers, who now boast a coaching panel of Hird, Thompson, Dean Wallis, Simon Goodwin, Sean Wellman and Brendan McCartney.

''Mark has confirmed today that he will be joining the club in December,'' he said. "He went to the coach and the players directly and told them that he wanted to take up this opportunity, he wants to support this team and he wants to be part of this club going forward."

''He wants to be part of the team, not as a senior coach but to support James and be part of the coaching team.

''It's fantastic news for the club and for James - it's a great moment. We are really delighted and excited by this development. 'Bomber' comes back to the club where he was a premiership captain and played in three premiership teams. It's a great moment.''

Asked as to the whereabouts of the new signing, Hamilton referred to the words Thompson uttered whilst resigning from Geelong a month ago: "Bomber made it clear when he left Geelong, a club that he gave wonderful service to for eleven years, that he would need and require an extended break and that's what he's doing at the moment."

Thompson will begin his new role at the start of December after returning from his break.

"We respect that he needs a break, we want him to go away and take that break and come back ready to guide these players forward," Hamilton said.

Hamilton refused to divulge when exactly Essendon approached Thompson and began the discussions with the two-time premiership coach.

"We've approached him in recent times and in respect to the process we won't be commenting on the actual day-to-day bearings of how we got this coaching group together. It's pretty clear we don't want to make any further comment on that," he said.

Even though Essendon have been talking to Thompson for some time, his presence at today's training took the coaching staff and the playing group by surprise.

"It wasn't unexpected that he would take the position, what was unexpected was that he would come to training today and accept it."

Although Hird was said to have flown interstate on a recruiting mission he gave his thoughts via a club statement this afternoon.

"He has built a list that has achieved the ultimate success from scratch and his depth of knowledge will be invaluable to the Essendon coaching group for 2011 and beyond," Hird said.

"Between myself, Simon Goodwin, Dean Wallis and Sean Wellman we have got a fairly young coaching group. Brendan McCartney obviously adds a fair bit of knowledge and experience but the senior coaching experience that Bomber adds to the coaching panel will be of significant benefit to the club's aspirations of future success."

Hamilton confirmed that Essendon had been in contact with Thompson's former team earlier in the day to inform them on Thompson's decision.

"We've had contact today with the senior members of the Geelong Football Club and in all honesty they have wished us the best," Hamilton said.

Thompson played 202 matches for Essendon from 1983-96 including the 1984, 85 and 93 flags. He was captain from 1992-96. At Geelong he coached 258 games for 160 wins including two premierships from 2000-2010.

Thompson and Hird were teammates in Essendon's 1993 premiership team, which Thompson captained.

When interviewed on Monday, Hird stated that a contract had not been signed and that he could not elaborate on the issue any further.

"To my knowledge there hasn't been a contract signed. I know Mark's on a break at the moment and we're respectful of that. I spoke to him a couple of weeks ago... When we have something positive and definitive we will come and say it," Hird said.