Class classification for the nation

On the subject of class, I was informed by the BBC's Great British Class Calculator that on balance I'm most closely identified with the Emergent Service Worker group. Frankly, as someone who yesterday evening spent more than £5.50 on pine kernels in a branch of Waitrose without batting an eyelid, I'm appalled that it failed to recognise me as a bona fide member of the Established Middle Class group...