Just, nope - two words: "Peace Dividend". The Anti-Fascist Defence Barrier was down, Western Group of Forces had gone home, Fukuyama was smugly insisting it was the End of History, and Options for Change was in the offing.
There wasn't even a production contract for TIALD, and that had actually earned its salt on GRANBY - so, low-level navigation tools like SPARTAN just wasn't going to happen. Anyway, why bother? Tornado had a rather good FIN3110 Inertial Navigation System, designed and built by the people who sponsored me through University (very good link). First of the Ring-Laser Gyro systems, and (as I understand it) accurate as all f**k - certainly better than the US kit of the time (they didn't get RLGs until the F-15E and late updates to the F-111).
As an apocryphal note, there was originally going to be a Inertial Navigation System in Challenger 2 - with a GPS update mechanism (remember, GPS in the early 90s was an utter PITA; twenty minutes standing still, just to get three satellites in view, the electronics were barely up to the job; and no-one trusted it to "not die" twenty seconds after Ivan the Gasman started chucking ASAT and EMP around). Anyway, it got deleted from the requirement as too expensive/unnecessary, and CR2 was left with paper map or GPS, nothing in between.
The Tornado Midlife Update Programme was nearly cancelled in the early 90's because the Treasury refused to fund the project.
The R.A.F. was able to persuade the Treasury to pay up albeit at the expense of certain items of new equipment.....SPARTAN being the most important/severe of them.
There was also a plan to buy 26 new build Tornado GR 4s to replace those lost In accidents/Granby but that was cancelled also.
The money for the Tornado Midlife Update Programme came from the savage Front Line First Budget Cuts.