Somewhat confusingly, Surrey County Hall – the headquarters of Surrey County Council – is in Kingston upon Thames. County Hall was built in 1893, but Kingston has been in Greater London since 1974. To add to the confusion, "the county town is traditionally considered to be Guildford" (to quote Wikipedia).
IMHO, "Kingston upon Thames" should have been accepted as an alternative answer to this question (unless the word "traditional" was included in the question).
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