Ellen Eliza Richardson (also known as 'Nellie') was born in Hackney, London. She and the painter William Kirkbride BLACKLOCK were married in Chelsea in 1909. In 1910 they had a daughter, Eleanor Irene. Nellie is known to have modelled for her husband for a series of paintings between 1910 and 1917. 

About 1912 the family settled in Walberswick in Suffolk for a few years, but later moved to Leicester, then Polperro, where William died in 1924. Nellie was a painter of flowers in watercolour, exhibiting at the Royal Academy Liverpool, the Walker Art Gallery and the Royal Institute of Painters in Watercolour.

Nellie re-married in 1927 to Edward J B Sewell in Kensington. She continued to exhibit, and died in the Penzance district in 1956, aged 68.