Loan deals followed with the Shrimpers, where he enjoyed a great six months scoring the winner against Leeds, and Championship Reading, where he was involved in their play-off semi-final against Burnley.
Harding had been training with Yeovil FC to keep himself fit.
Phew! I'm out of Yeovil
However, it's the team from St.Mary's who have coughed up the wages the Blues couldn't afford as Dan becomes the first signing by new boss Alan Pardew on a freebie.
A shame but with Saints losing players from their relegated Championship side on a regular basis, six have now left, Pardew will still have plenty of work to overturn a minus 10 point start, for going into administartion, and turn them into promotion candidates.
The investment from new owner Markus Lieberhr will obviously help, but enough to see them do a Leeds in their first season in the third tier when they reached the play-offs, and they started with minus 15, we will have to see.
Shrimpers will have an idea how they've started by the time Southampton play at Roots Hall on Saturday October 10 with the return fixture on the last day of the season.