The GR.1 is really what the Tornado is all about, an all weather, low level, deep penetration strike aircraft.  The airframe, engines and radars were all designed with this role in mind.

First impressions of the GR.1 tend to be misguided, it looks short, dumpy and the huge fin looks out of proportion to the rest of the airframe.

The large tail is necessary for longitudinal stability, once the wings are swept back they play little part in controlling the aircraft, the large all moving tailerons and spoilers take over. 

The GR.1s engines are also optimised for low level flight, the RB199 turbofan was designed from outset to provide high power at low level and still be reasonably economical.

I understand that most of the British GR.1 fleet now has the RB199-34 103 engine, whilst some of the older airframes are still fitted with the RB199-34 101.

The GR.1 entered front line service with 9 Squadron at RAF Honington.  No 9 Squadron were the first to use the Tornado for the 1985 Red Flag exercise in the USA.

142 GR.1 airframes are being upgraded to GR.4 standard, for a more detailed look at the actual upgrade please visit the GR.4 page.

Several major variants of the GR.1 package were developed, the two most obvious being the GR.1A and GR.1B. Although the GR.1B designation has now been officially dropped as the Sea Eagle launch capability will be included in the GR.4 upgrade.