Johnston decided against a move

Johnston, capped by England in Argentina last summer, was out of contract this summer and had been linked with a move to Leeds or Harlequins.

"Ben has been playing very well over the last month or so," said Saracens coach Wayne Shelford.

"We know what he's capable of and we know that he's going to be a great asset not only for Saracens but for England too."

Johnston, 24, who plays for England against the Barbarians on Sunday, said he was "made up" to be staying at Vicarage Road.

"I've been at Saracens for quite a few years now and couldn't really imagine playing anywhere else," he said.

Departures

Saracens have lost England prop David Flatman however, who has signed for Bath.

The 22-year-old has won eight caps since making his Test against South Africa in 2000, and will be on the bench against the Baa-Baas.

They will also be saying farewell to Wales centre Tom Shanklin, who has signed for Cardiff.

He has shown at Newport and for Fiji that he has good leadership qualities Shelford on Simon Rawalui

The 23-year-old is heading home to Wales with Saracens having already recruited Wallaby centre Rod Kafer from Leicester.

The club had already bolstered their personnel for next season by signing Newport's Fijian lock Simon Raiwalui and emerging England second row Alex Codling from Harlequins.

Auckland-born Raiwalui has won 41 caps for Fiji, captaining his adopted country 10 times, and previously played in England with Sale before his four-year spell in Wales.

"He has shown at Newport and for Fiji that he has good leadership qualities which will be of use to us here," Shelford added.

Codling won his first England cap in last summer's Test victory in Argentina, and is recognised as one of the Premiership's leading line-out ball stealers.

"He does his homework on the opposition and he's very professional," Shelford added.