2.4.1. The sign to diagram 510 (S2‑2‑7, see Figure 2-8) should not be used to indicate the approach to a roundabout where adequate warning is conveyed by a map‑type advance direction sign or where the roundabout is clearly visible to approaching drivers. It may be used with supplementary plates to diagram 511 (S2‑3‑1), 513.1A (S2‑2‑4) or a distance. “Adverse camber” may be used in place of the 513.1A lorry adverse camber plate. The roundabout warning sign should be used only for true roundabouts. It should not be used to give advance warning of a gyratory system or where the approach to an otherwise standard roundabout is controlled by signals.