It can also depend on people's politics vs who is on power. In general British anti-vaxers are left wing (very lefty affluent hippie types - you can see this from the areas with low MMR rates), and even more so during covid when a right wing government was in power. There is evidence for this in a survey KCL did of anti-vaccine beliefs during covid. I personally know of British students who declared they would not have covid vaccines because they "did not trust the Tories"