Can't remember if it was then (2001/2002 if memory serves) or a few years before of the hiring of RES 47s a couple of days before Pathfinder were due to run a charter advertising first use of RES 47s on a passenger train. Sure someone else could clarify.
It would have to be considerably earlier. The RES 47/7s were put to work on charter trains from pretty much the moment they began to be released from works in 1993, following directly on from the lives that many of the locos had previously led as 47/8s. 47783 hadn't even been painted out of Intercity swallow livery from its' previous incarnation as a '47/8' before it found itself on railtour duties.
Virgin Crosscountry could reliably be expected to throw out RES and Fragonset 47s, and stranger things still on occasion, in place of the booked 47/8s (They could reliably be expected to be unreliable!). I remember being pleasantly surprised when BR green liveried 47488 rolled into Newcastle at the head of a heavily delayed Crosscountry service, some time in the late nineties. Great from an enthusiasts’ point of view, but fairly hopeless if you were actually hoping to get anywhere! Mind you, I do recall some good runs with 47/8s under Virgin, too.