Not 100% sure how it works. Can't be 1% for every £50k I don't think - the weighted average council tax in Warwick DC is £1,190 per household so a 1% rise across all tax bands would generate about another £635,000 per annum.
Are you sure it wasn't £1 per £50k? That would add up better.
Perhaps someone who knows more about how council tax works could provide a more accurate estimate of the real rate rise people will experience?