Firstly - it is clear unacceptable racism by the Lady in Waiting - on top of the verbal comments she also brushed the other lady's hair aside to look at her badge, which is a bit too assertative and over bearing for someone you have just met at such a meeting. The older lady was probably brought up with values that are unaccepable today and has not modified her views to reflect changes in society.
Secondly it highlights to me the increasing differences in UK society, Upper class, over 80s from the shires will not mix much if at all with people living in Hackney or they may have a view of society from say 45 years ago. In 1977 the UK was comprised of around 3% of people who were from a non white racial type, now it is around 17.5%. Where I live the racial profile is radically different from say London abnd Birmingham, but wasn't in the 1940s.
We hopefully all on here recognise anyone can be 100% British and non white, but I noticed some of my relatives when they entered their 80s were stuck in a different age, they didn't use the internet, they watched a lot of old TV, in fact went backwards (as far are recognising changing society), loved watching TV dramas about a different age particularly their own childhood (WW2 say) and certainly in 2022 I would not have had those relatives representing an organisation at social gatherings such as was taking part at Buckingham Palace. I am sure there are some very sharp 83 years old, but some start to show signs of dementia, mental health issues etc. I don't know this Lady in Waiting, but her mental state could be changing too? Some of her questions seemed so over the top which also hints to some mental health issues e.g what part of Africa are you from? when there had already been a dialogue about her background.