I remember this quite vividly as I was not far behind the said banner. It was in the section nearest their main stand. Bada Bing is correct.
It was a number of Ulster Flags all the same size stitched together and it actually had a union flag in the center of it. Guys were holding it up and police were sent in to pull it down as no doubt it was wrongly construed as being 'sectarian'. They were repelled! There was actually a photo of it at the time and what helps my memory was the chant went up of 'Ulster Says No'. There was a real feeling of defiance and no way were they coming in to take it down.
This was around 91/92 and at that time, while there was the odd flag/banner in the grounds it wasn't massively widespread for clubs to have them at domestic games. More big away trips. For me, this incident above changed this
There was a piece in Follow Follow about and it may actually have made the papers and was incorrectly reported. Off the back of this, the fanzine then put out a call to arms for everyone to mobilise and dig out any banner they had and turn up at the next game at the Piggery and get them up. It was the first of the modern 'Flag Days'. This led to the resurgence of the bringing of flags to games. I remember reading the rules in the FF which was along the lines of no gang names, no swearies and no paramilitary themes. I believe it was the 2nd Flag day there where the photo was taken which eventually was made into the famous poster that was given free with the fanzine of the full Rangers end with hardly an area not being covered with a banner of some description. It also coincided with us playing in the very first Champions League format and with the influence of European fans doing similar, our supporters and RSCs started getting their own ones made up.
Make no mistake that our support led from the front (coordinated with the fanzines) with creating atmospheres during this period ( we also had the bog roll day!)and it was some time until the Tims caught on and started to have any kind of attempts to keep up with us.
Oh and it was also mentioned in this thread about us all singing along to 'Grand Old' Team; with the Ha Has. This was started at Parkhead by us as we lorded it over them continually during the 90s and it took quite a period before they beat us and got the chance to retaliate by doing it to the Billy Boys. This got more attention as the cameras of course were above the Jungle, but again, we had been doing it way before this, they were just nicking our support's ideas