Love it! Great use of Sherlock Holmes canon (I love Ron and Harry being fen and Snape's constant jealousy of Holmes). Hermione as a suffragette was wonderfully appropriate, and I adore your Dumbledore and Minerva! The fountains - awesome! Snape hallucinating his death - brilliant. Mrs Figg knowing Harry's secret - so fitting!
I think what I liked best was the British-ness and the fact that you managed to surprise me in the end. An all around wonderful story.