Brentford CEO Mark Devlin has revealed that midfielder Jonathan Douglas has left Griffin Park to join the Blues.
Devlin, speaking to Sky Sports News on the Brentford leg of their 92Live trip around all the English league clubs, confirmed that the deal is done.
Yesterday, Douglas was reported to have agreed a one-year contract with an option for a second season at Town, having undergone a medical in the afternoon.
The 33-year-old was due at Portman Road to put pen to paper this morning with the Blues set to formally announce his signing on what's understood to be a free transfer later today.
Monaghan-born Douglas, whose partner is Sky Sports News presenter Natalie Sawyer, moved to England in 2000 when he joined Blackburn Rovers. While at Ewood Park he spent time on loan at Chesterfield, Blackpool and Gillingham before moving on to Leeds in 2005.
After four years at Elland Road, the 6ft tall holding midfielder moved to Swindon before he joined Brentford in 2011.
Douglas, who has been capped eight times by the Republic of Ireland, signed a new contract with the Bees in February but is not in new manager Marinus Dijkhuizen's plans and last month he was told he could move on.
"He is not part of the squad and is training separately [with the U21s]. There is no future for him," Dijkhuizen told BBC London.
"We decided it is better for him to move on - for his future and for the future of Brentford."
Last season Douglas made 46 starts and scored eight goals as the Bees finished fifth in the Championship, one place above Town. Coincidentally, the teams meet at Griffin Park on Saturday.
Last week, the Blues missed out on signing another Brentford player, Northern Irish winger Stuart Dallas, who is set to join Leeds United in a £1.25 million deal.