RLC were probably traveling in convoy as part of a counter-terrorism effort. Where possibly, the army will always travel in convoy (our last one stretched back 2 miles!

)
That one included RLC, Infantry, AGC and REME. The Land Rovers can go faster than the 4-tonners but have to stay at a lower speed and stay in convoy.
It's common sense really, no one would dare attack a 75 vehicle convoy

They don't have any powers per-say, but would you argue with an armed soldier, knowing that all his mates were around?