What I want to do is have:
Sheet1!A2 take the value from Sheet2!ColumnE, where Sheet2!ColumnB = Sheet1!F2.
I think it will probably be some sort of lookup, or maybe a pivot table or something, but I can't get anything working so far. It's about 15 years since I last used my advanced Excel skills, so not only is everything very rusty, things have changed a bit between Excel 5 and Excel 2010...