hi cando
the 1851 marriage cert states - father
Joseph Clark
Elizabeth was baptised as an adult in 1851 in Kirton Lindsey (after marriage, as "wife of Richardson")
I have not found her in the 1851 census but from memory (away from desk at the mo)there was, either in the same household as Richardson or nearby, a Rebecca Clark

BTW Emma's birth cert states mother Elizabeth Clarke age 34 born London
Lou