British English past tense of dream (American English typically uses 'dreamed').
From Old English dreoman. The -t ending is another case where British English retained the older Germanic past tense form while American English shifted to the -ed form.
Just like 'learnt' vs 'learned,' British English speakers kept the old Germanic grammar while Americans standardized to -ed, and both happened around the same time period when America was asserting its own English identity.
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