Saints have completed the permanent signing of left back Ryan Bertrand on a four-and-a-half year contract.

The 25-year-old has been in superb form for Saints since joining on loan from Chelsea in the summer.

His loan spell was set to last the whole season but Saints were given the chance to exercise their option to complete a permanent deal before the close of yesterday’s transfer window and had no hesitation.

Though the fee is officially undisclosed, it is believed that Saints paid in the region of £10m for the man who won the Champions League with Chelsea.

Bertrand has proven to be an excellent replacement for Luke Shaw, who departed for Manchester United last summer, and has already made 27 appearances for Saints, scoring two goals.

After serving a three game ban for his red card against Swansea on Sunday, Bertrand will be aiming to finish the season on a high with Saints, and to force his way back into the England squad.

Though the left back spot is a competitive area, Bertrand has been excellent this season and has been harshly overlooked by Roy Hodgson.

He won the last of his two caps for his country in 2012.