I'll use the excuse that I was focussing on getting the ironing done, but I have no idea why colonialism is being raised here. This is a comment more about how it may well have gone over a lot of heads, than a dig at anyone.
If anyone has time to put together a couple of paragraphs in a spoiler for my education, then I'd read with interest. In fairness, lots of Dr Who goes over my head, and the 'arc's are mostly a waste of time for me. I feel like I'm more tik tok generation. But discrete episodes with strong characters (Doctor and companions) are about all I can deal with.