Town created chances but with no rewards again. Jon Walters and Alex Bruce both going close for Blues but Marek Saganowski's first minute goal gave Saints the win.
Walters saw a header superbly saved by Kelvin Davis while Bruce and Sylvain Legwinski failed to convert headers from good positions.
Jim Magilton made two changes to the side that went down to narrow defeat by Wolves, Owen Garvan starting in front of Jaime Peters with George O'Callaghan coming in for Walters, who was a major doubt for the game after taking a heavy knock in midweek. The new signing from Chester starting on the bench.
Saints included three former Town players in their line-up, Chris Makin, Jermaine Wright and Davis, as well having as ex-Blues' boss George Burley in charge.
Town got off to the worst possible start on just 52 seconds, Matt Richards penalised for a foul on Djamel Belmadi with Saganowski losing his marker to beat Lewis Price with a header from Bale's devilish free-kick.
Bruce had a great chance to level the scores on the quarter hour, the defender heading over from a corner only six yards out.
Price saved comfortably from Andrew Surman's cross, the Welsh international doing superbly to deny Kenwyne Jones seconds later after the Saints' striker had escaped from Jason De Vos and got in on goal with only the Town 'keeper to beat.
Blues, after that initial first minute setback, threatened to get back in the game before the break and Gary Roberts blasted well over from a good position after Alan Lee and George O'Callaghan had linked up well.
Price gathered well again from Surman's cross under a challenge from Jones while at the other end, Town created another good opening, David Wright's cross headed wide by Legwinski from 12 yards, the Frenchman having more time than he realised.
Davis in the Saints' goal made a smart save from O'Callaghan after a surging run from Dan Harding had caused problems in the home defence as Town finished the half moving forward.
Balmadi picked up the first yellow card of the game in the opening minute of the second-half, tugging back Richards.
Saints were inches away from extending their lead on 55 minutes, Jones blasting a shot against the post when in a great position.
Garvan, making his 50th appearance for the Club, almost fed O'Callaghan with a neat pass while at the other end, Jones left fly again from the angle, the ball screaming past Price's goal.
Garvan's battling qualities created another opening for Blues but Chris Baird cleared from the on-rushing O'Callaghan before Town made their first changes, Peters and Walters replacing Richards and O'Callaghan as Blues switched to 442.
Wright and Peters linked up well on the right, the cross scrambled clear by Claus Lundekvam then Walters sent a diving header goalwards that was superbly beat out by the diving Davis.
Burley made his first change with 78 minutes on the clock, Belmadi making way for Pedro Pele. Danny Haynes then replacing Lee with Bradley Wright-Phillips coming on for Saganowski in a flurry of changes.
Town had run of corners, Legwinski and De Vos both throwing themselves into the mix in a bid to find an equaliser, Makin showing great awareness to chest the ball back to Davis under pressure. Roberts then booked as the game entered added on time.
Blues pressed continually for that leveller but could find no way past Davis as Town's goal drought stretched to six games, setting up an important home match against QPR at Portman Road next week.
Town: Price, Wright, De Vos, Bruce, Harding, Roberts, Garvan, Legwinski, O'Callaghan (Walters 69), Richards (Peters 69), Lee (Haynes 81). Subs not used: Supple, Casement. Booked: Roberts.
