The queen banning black workers from her offices until the 1990s
(I’ll have to respond to this in individual posts…otherwise it will be far too long 😀)
The Queen’s household - in line with most of society in the 1960s - did not permit
“coloured immigrants or foreigners” to take clerical roles (they were allowed to work as domestic servants).
It is unclear when this practice ended. Buckingham Palace has confirmed that its records showed that people from ethnic minority backgrounds were employed in the 1990s. It did not keep records on the racial backgrounds of employees before the 1990s, so it cannot identify when the rules changed.
As for Britain as a whole, the UK government chose not to adopt various EU laws to protect people from discrimination until the Blair government post-1997. The key act in the UK wasn’t actually passed until 2010. Prior to those changes, discrimination on the basis of race/sex/sexuality and religion was alive and well and practiced all across the UK
So you can definitely judge the Palace for their attitudes in the 1960, but you will need to judge the whole country for them too - the Palace was absolutely not out of step with current social attitudes and values there. Your hypothetical Head of State will inherit a Department that had exactly the same historic practices, by the way…