It goes back to the 1982 domestic series, I think. India and Pakistan both played three tests in England. Both complained to the TCCB about Umpire Constant whom they said was not even-handed and had given preference to England in various lbw shouts.
When Pakistan returned in 1987, they asked the TCCB not to put Constant in the international matches but this request was refused. The PCB and skipper Imran found this high-handed and imperialistic. The series was not played in good humour. There was crowd trouble, pitch invasions and one fan was stabbed. At the end of the series I recall the Pakistan manager - name of Haseeb Assan?? - making dark comments about “using our own umpires” in the return series.
So the PCB picked Shakeel Khan, who should not have been umpiring a club match, and Shakoor Rana who was highly officious. A number of truly bad decisions were taken, most (though not all) against England. Broad refused to walk when given out lbw. Someone else was given out caught after the ball beat the edge by six inches. Things deteriorated and eventually Gatting blew up after another officious decision from Shakoor.
I think the PCB wanted to teach the TCCB a lesson and Gatting was not smart enough to realise he was being deliberately provoked.