I've heard this story but can't immediately find any corroborative reference so it might be apocraful
Just after the second world war the damage to the house of commons was being repaired and George VI expressed an interest in looking around he was given a tour or the work ans signed the visitors book "Mr. Windsor".
Interesting, Jake. So the question should be worded 'admitted, in their capacity as monarch,'. Good thinking by George VI, not to sign as 'George R' Very diplomatic!
as I understand it, and I may be wrong, they can't go in unless they're invited. George may have been invited. For all I know, others have been. I don't know that there's an actual ban.
Between 10th May 1941 (the bombing of the Old Chamber) and 26th October 1950 (the opening of the rebuilt New Chamber) that damaged area of the Palace of Westminster technically did not contain the Commons Chamber. MPs were relocated during reconstruction and in whichever building they assembled for their parliament it would be the de facto "Commons Chamber".
If George VI did inspect damaged areas of the Palace of Westminster in the immediate vicinity of St Stephens Chapel and the "Old Chamber", he could at that time never have been within the sitting Commons Chamber.
dont doubt he was admitted on all his visits up until the last one, but i read somewhere that when he turned up with a bunch of soldiers to arrest his 5 MP's, some members tried to block the doors, and the soldiers had to force an entry...doesnt change anything...also read somewhere about the King nipping in to have a look and talk to workmen after WW2