By Andrew MacAskill DARTFORD, England (Reuters) – Silvia Sherwood believes it is time for a change of government in Britain at this year’s election, saying an economy that forces cash-strapped elderly women to seek warmth in shops needs to be fixed. In an era of deep divisions in Britain, voters like Sherwood are becoming some of the best predictors of who will win the election, living in a town where results have aligned with the national vote in every national election since 1964 – the longest consecutive record. If that track record is any reliable guide, then Prime Minister Rishi Sunak sho…