Chaplow completed the move this morning, went straight into training with his new team mates and is expected to make his debut for the FA Cup Semi-Finalists in their Championship clash against close neighbours Charlton tomorrow lunchtime.
It's over eight years since Chappy, now aged 28, left Turf Moor. That was on the last day of the January transfer window in 2005. That was at a time when we weren't subject to transfer windows but West Brom was his destination and they were due to being in the Premier League.
He moved to Southampton on loan in 2006 and his next move saw him return to the North West and Preston. Problems with manager Darren Ferguson eventually paved the way for a return to Southampton, initially on loan, in September 2010.
He's made just six appearances this season, three starts in the Capital One Cup and three substitute appearances in the Premier League, but only one of those has been since October.
His loan should see him available for Millwall's FA Cup semi-final against Wigan and ends on 11th May the day of the FA Cup Final. Could we have an ex-Claret in this year's FA Cup Final?