Traffic inbound to Gatwick is vectored because it is deemed to be 'radar only' approach control , actually done from London Terminal Control at Swanwick. Procedural plates are only for backup in case of an (unlikely) total radar failure.
Radar vectoring is more efficient than procedural approach as separation on final approach can reduce to 2.5nm if there are no departures and slightly more if there are departures whereas it would be time based without radar probably something like 5 minutes, although this would need to be confirmed by someone current on Gatwick Approach.