How did Hyacinth and Richard meet on Keeping Up Appearances?

This question was never addressed during the series. Keeping Up Appearances was on BBC from 1990 until 1995 with specials airing after that time. The DVDs of the entire series consist of 8 disks which begin with the first episode and include the Christmas specials. Hyacinth and Richard never discussed their courtship, their son Sheridan was never seen, and the question of how they ever got together is a mystery.