The Tornado GR.1B is a modified GR.1, it is capable of carrying the British Aerospace Sea Eagle missile.
There are next to no visual cues to differentiate a GR.1B from a GR1, unless it is carrying the above mentioned missiles.
The GR1. B is a replacement for the Blackburn Buccaneer.
Twenty six airframes have been modified for this role including two trainers. All modified airframes came from Batch 3 and are powered by the -103 variant of the RB199 engine.
ZA409 & ZA411 were the proof of installation airframes, they are both trainers.
ZA407 was the first production airframe and flew as a GR.1B on 18/09/93.
The GR.1B airframes were as follows,
It should be noted that the GR.4 upgrade program will see all GR.4 airframes capable of deploying the Sea Eagle missile. As of the first quarter 2001 the GR.1B designation has been dropped.