New gray market EF 24-105 L are well under £600, for example https://www.e-infin.com/uk/item/3270/canon_ef_24-105mm_f/4l_is_ii_usm_lens_mark_2_(white_box)
Doing some number crunching on the RP, list is circa 43% less than the R, so in due course the gray market will be under £800 gbp