Trend: Fandom. Sienna Spiro’s “Great Expectation” is spending a third consecutive week at No. 1 on the UK Official Singles Chart, but the bigger signal is what is happening around the hit. The British artist now has three songs simultaneously inside the Top 40, suggesting listeners are moving beyond discovering one track and toward discovering Spiro herself. “Great Expectation” may have created the breakthrough, but sustained attention, catalogue exploration and growing artis