Clearly this thread has run its course!...and many thanks to all who have contributed to the subject.
To draw a line under it I would summerise that legally, the notice remains valid irrespective of any change of RP. However, there would be a defence of due diligence available to anyone in the Court following a failure to comply.
To avoid this defence being realistic, it would be prudent for a FRA to a) copy the notice to the owner, head office etc, and b) periodically monitor the premises to ensure compliance.
During this revisit, becoming aware of a new RP, the FRA has the option of doing nothing, providing a copy of the original notice, or re-issuing a new notice to the new RP (subject to conditions being confirmed as the same).
This choice will depend on individual circumstances, but it would appear that the second option of providing a copy of the original notice will in most cases suffice.
Thats how I see it anyway!
Thanks again