The BLM movement has attracted a lot of attention on an issue that has been largely swept under the carpet. Instead people debate those issues around racism, deny history, claim the empire was benign or equate other topics to being of equal importance - all so the actual issue should not be tackled. The greatest aide to the racist is apathy.
I do not believe that the UK , Spain or Ireland are particularly racist countries, however, the majority of the populations just does not care. It does not impact them and you are talking about something that directly effects just 6% of the UK population.
However, In England there is a nasty underbelly of people who consider the impacts of slavery and empire an irrelevance and that through sheer accident of birth, they have inherited the 'Great' in Great Britain but on closer examination of their lives their contribution to the condition of the human family is negligible. The keyboard warriors who want to talk about your roots or proclaim the country was better in the 1950s, 60s, 70s etc. any day have been emboldened. Its a fascinating topic.