Hi Hermione,

Yes l have seen that, and gone through his diary pages, but there is no mention of Reisner reopening GIII-a or GIII-b.
His drawings of these substructures are carbon copies of Perrings, as are his measurements when converted from imperial, and in his 1931 work he refers the reader to Vyse & Perrings work for more detail on them. His priority was directed to the temples, and maybe he was content with Vyse's work on the substructures.
In Petries time they were closed up; Grinsell in the 1940's report they were closed up, and same again in the 60's as reported by M&R.
It would seem strange that no one has been inside since 1837, especially as Vyse admits that in the case of GIII-a he gave up clearing debris from the burial chamber for want of air.