The resignation of Margaret Thatcher in 1990.
Probably this.
I say probably because I have some very vague recollections of things earlier, but they might be later creations. I also remember being confused about the fact that there was a war about golf, but don't know when this (the confusion) happened. The first really, really, really clear political memory (one that can be recalled as if it were yesterday, rather than through a vague fug) would be the death of John Smith.
My memories are often more pronouced if I can remember my parents being affected by it; such as Thatcher's resignation and John Smith's death. Though for the latter, the big death (to my 10 year old self) that year was Roy Castle off
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