The Red Steer 2 was actually a modifiaction of the Lightning radar, AI21?. The AI21 had a conical capability of +/- 60 deg. As the Vulcan was not intended to such extreme manouevres the Red Steer sweep was different. It was +/-70 deg horizontally and +/- 20 deg vertically. By and large it meant that it could remain locked on or detect slight better than the AI21.
The rapid scan mode was slightly different. When it was anticipated that the fighter was in the launch bracket the radar could be switched to narrow scan +/- 5 deg. In this mode it could detect an AAM separation from the launch aircraft and fire the appropriate decoys - IR or chaff.
Remembering that this was 40 years ago this is pretty advanced technology.
However, on one exercise, I remember looking at the RS display. It looked like the B17 war films with the 'sky' full of contacts ie out to 20 miles. The AEO had to look for contacts sliding in to the 'static' targets which would be the interceptors doing stern arc conversions. Of course once in behind another target they would be same-way same-day and potentially unnoticed by other AEOs.