As I see it, the answer depends on how you choose to define RP. Do you consider it
- the implicitly agreed model of good BrE speech?
- a codification intended mainly for EFL pedagogical purposes?
- or an objective description of how people at the top of BrE social stratification actually speak?
Here is what the Cambridge English Pronunciation Dictionary, says (17th edition, 2006, Daniel Jones, edited by Peter Roach, James Hartman and Jane Setter) on the subject of r links.
So as far as intrusive r is concerned you could say that EPD prioritizes “safe” advice to learners over the documentation of reality.
The raised r symbol replaces the asterisk used by Daniel Jones in earlier editions of EPD. While recommending foreign learners to use linking r only in such cases, Jones also (12th edition, 1963) carefully and in great detail explains how intrusive r in words ending in ə, ɑː, ɔː but not transcribed with the asterisk “is a very noteworthy feature of south-eastern English”. In the current EPD, Jones’s page-long discussion has been reduced to the two sentences you see here.
The environment in which intrusive r is perhaps most disfavoured is in word-internal position, between a stem and a suffix beginning with a vowel sound. Thus the pair sawing and soaring are distinguished by some, but certainly not by all, real-life RP speakers. EPD, in line with its policy stated above,
Tomorrow we’ll look at ODP.